The U.S. Census Bureau American Community Survey application program interface (API) is a valuable programming interface for quickly and efficiently adding census data to your R code for analysis. It’s an extremely efficient way of doing data analysis in R without having to pull, format and organize census tables into a CSV or spreadsheet.
In order to use the census API, you will need to apply for a census API key, which takes only a few minutes. You then will need to install the key using the function census_api_key.
census_api_key('<key>', install=TRUE)
Once the key is install, it doesn’t require to be installed again, unless it expires or you apply for new key. Going to the U.S. Census website and searching for the API is how to apply.
The get_acs R function gives you the ability to pull in multiple years and categories of survey information for demographic information including race, household income, marital status, employment, etc. It’s a power feature for analyzing survey and census data in tidy format.
ACE variable data can be enumerated in a list with with descriptive names for easier classification. All variables are indicated by a document id (for example S1702_c01_018, S1702_C01_019, etc.).
You can also choose to include margin of error (moe) or not. Visualizations can be in typical R GGplot library mode or included into maps. All ACS information includes IDs that categorizes survey data.
Human Genome variation analysis is a popular biomedical and biological typical used for finding disease, developing treatments and discovering a wide array of human genetic variation that can study the impact of disease and medical treatments.
Reading VCF files into R.
The vcfR package was designed to work with data from VCF files. The vcfR package was designed to work on an individual chromosome. A VCF file structure is a standard file format for storing variations for genomic data and is used by organizations to map human genome variations. It used used for large scale variant mapping. One example is the International Genome Sample Resource (IGSR).
It contains headers
CHROM
POS
ID
REF
ALT
QUAL
FILTER
INFO
FORMAT
The name of the chromosome.
The starting position of the variant indicated.
Identifier
Reference allele. An allele is one of two or more alternative forms of a gene that occur by mutation and found in the same area of a chromosome.
Alternate allele
Quality score out of 100.
Pass/Fail. Did it pace quality filters.
Information about the following columns.
Format of the columns.
The following libraries needed to load and process VCF files.
BAM files contain the RAW genomic data an are typically very large. Along with a wide array of tools that can read BAM files, R has many functions that can process BAM data. BAM files also come with an index file that makes it easier to find information with the larger BAM files.
To load the BAM file libraries, you can install them directory into R or download the Bioconductor packages from https://www.bioconductor.org/.
if (!require("BiocManager", quietly = TRUE))
install.packages("BiocManager")
BiocManager::install()
if (!requireNamespace("BiocManager", quietly = TRUE))
install.packages("BiocManager")
BiocManager::install("Rsamtools")
BiocManager::install("pasillaBamSubset")
(bf <- BamFile("D:/temp/raw1.bam"))
(bf <- BamFile("D:/temp/raw1.bam",yieldSize=1000))
seqinfo(bf)
(sl <- seqlengths(bf))
#quickBamFlagSummary(bf) -- Realloc cound not re-allocate memory problem
(gr <- GRanges("chr4",IRanges(1, sl["chr4"])))
countBam(bf, param=ScanBamParam(which = gr))
reads <- scanBam(BamFile("D:/temp/raw2.bam", yieldSize=5))
class(reads)
names(reads[[1]])
reads[[1]]$pos # the aligned start position
reads[[1]]$rname # the chromosome
reads[[1]]$strand # the strand
reads[[1]]$qwidth # the width of the read
reads[[1]]$seq # the sequence of the read
gr <- GRanges("chr4",IRanges(500000, 700000))
reads <- scanBam(bf, param=ScanBamParam(what=c("pos","strand"), which=gr))
hist(reads[[1]]$pos)
readsByStrand <- split(reads[[1]]$pos, reads[[1]]$strand)
myHist <- function(x) table(cut(x, 50:70 * 10000 ))
tab <- sapply(readsByStrand, myHist)
barplot(t(tab))
(ga <- readGAlignments(bf)) # allocation of memory issue. If the BAM file is too large.
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With the resignation of CEO Jack Dorsey as the executive leader of Twitter, I began to reflect upon the platform and what exactly the brand stands for. Twitter has been widely criticized for being a megaphone for extremism, hatred and anti-democratic ideology. My personal experience with Twitter has been one of desperate persuasiveness as I try to engage multiple people at once on issues that I care about. It’s very easy to get emotionally addicted to Twitter and invest a ton of emotional capital into it.
Microblogging, when it is healthy, can be a platform that engages multiple people at once very quickly who have varying points-of-view or advocacy, and watch as it get’s retweeted, liked or shared across social media. But people also use it to spread misinformation, harmful caricatures in real time, and watch as it becomes viral. My personal experience with Twitter has been like walking into a room with dozens of people arguing and trying to ask a question or bring a different point-of-view, and then quickly being dismissed, or insulted and at times being pushed out the room and the door shut behind me.
Ironically, this is exactly what happened to me once in real life. At a university I tried to insert myself into a conversation or topic that the vast majority of the participants didn’t think I should be involved in. And quite literally, the door was shut in front of me. It was humiliatingly painful; but I was very young and didn’t understand that I didn’t belong. Growing up, I was always taught that one of the greatest things about our country was diversity. Diversity of ideas, diversity of people, etc.
As I grew older, I realized quickly that the reality is far less ideal or utopian. Although we say we want diversity of ideas; really we want only our ideas to be accepted. And people who are different in race, culture, language, gender, identity are not always welcomed in the same spaces. That is a lot like twitter today. This became even more painfully evident when Twitter Spaces was launched. It quickly became a land mind as people battled it out in such racist hosting rooms as “Are there too many Black women in public?”, “Should White People Exist” and “Should Black People Exist?”.
As a data scientist, I studied extensively, the nature of associations on twitter and how people influence others based on who they follow and their own followership. For more information on this, read my article on association analysis in Twitter (for more information read my article on Apriori association analysis as a supplement to my Twitter article). What it taught me is that Twitter at its most beneficial is a “multiplier”. By multiplier, I am referring to Twitter’s ability to take information presented by someone on the platform, be it a blog, image, tweet, etc., and multiply that content to tens, hundreds, and even thousands of people near instantaneously better than any other platform.
So say for instance, your write a blog on your website. You may have hundreds and even thousands of people who have subscribed to your website. But that blog, in terms of engagement will likely not grow at the rate at which the reference to that article in a tweet would grow, keeping all other variables constant. For instance, if you have one hundred subscribers on your blog, and one hundred followers on twitter. The twitter reference will multiply your blog’s engagement. The same can be said for other platforms such as LinkedIn and Facebook (Meta).
My rule of thumb for Twitter now is to use it as a catalyst to bring more people to my site. Twitter is a multiplier and should not be used to have conversations. Express your ideas, then leave them there for people to engage. Remember that as a content creator, any engage – even if it’s negative – is a win! I also recommend creating a developer account and download Twitter feed data via the Twitter API. Twitter is really a great platform to understand this “multiplier” effect of social media.
I’d love to hear people’s comments on this. I’m open to have a conversation anytime on the topic. BTW, this article will be tweeted as well.
I’ve been a Database Administrator for over 20 years. Throughout the 1990’s and 2000’s, database administration had become a somewhat lucrative, in-demand job for many people working in Information Technology. Even today, the role of Database Administrators (DBAs) is critical for daily operational goals and maintaining customer applications. Recently, there has been a major shift in what employers are looking for in job candidates for IT positions. Less companies are hosting their own databases; and the need for big data systems in the cloud have created more opportunities for people with skills in cloud architecture, data pipelines architecture and data science tools.
That being said, I feel like this shift has put a lot of DBAs in a precarious position. Being a dedicated DBA is challenging and very time consuming and requires a very broad set of skills. Being a DBA is a full time job in of itself, and database administration does not easily translate to data science or data engineering, so if you want to work towards a job role as a data engineer or data scientist, you probably have to take that initiative on your own and do off-hour work to acquire those skills. Data science is the ability to create meaningful business actions from sometimes messy, uncoordinated data. Data engineering is the ability to take very large volumes of data and make it readily available to business stakeholders regardless of the type of data, where it is stored, or how it is stored. Most DBAs spend their time making sure that the bare metal (local or NAS) storage or provisioned storage of data is consistent, available, and secured with an “engine” that can easily query or perform transactions on this data. All the mechanisms needed to do this quickly, reliably and efficiently with no data loss is the challenge most DBAs face on a daily basis.
This is the very high-level comparison between the fields. But there are some very powerful nuisances that need to be taken into consideration if you want to change roles. For one, being a DBA doesn’t necessarily mean that you understand how to work with data. Data is messy, and one of the strengths of a data scientist is his or her ability to take data and clean it, transform it, removing duplicates, removing anomalies, etc. You then need to have the ability to sample and partition data, create models and score your model. Many data scientists possess knowledge in mathematics and statistics that allow them to perform deep learning or complex machine learning and data analysis tasks.
One common bridge to go from database administration to data science and data engineering is SQL. SQL is a very powerful language for querying data in a relational databases. SQL is also considered one the most popular languages for data science. There are many functions available in SQL to perform data science functionality in databases. SQL is a powerful language this is by far the most popular way to extract data from a database and deliver it to the business.
Most DBAs have had some exposure to SQL, with another group who have had training in programming procedural structured languages like T-SQL, PL/SQL, PL/pgSQL amount others. Therefore, transitioning to languages such as Python and R typically used in data science is less of a journey than starting with little programming experience at all. Both languages have libraries that utilize SQL and database commands.
Along with learning Python and R, learning many of the popular data science and mathematics libraries such as SciKitLearn and NumPy is also helpful. R is a great language to practice data science techniques as well. Look for the many online resources for learning data science. Visit my articles on the data science conferences and data science resources. Take online classes on LinkedIn Learning, Udemy, Datacamp and Coursera which all have starting tracks for data science. A lot of success in moving into a new role involves self-learning. Particularly if you are in a job position that doesn’t have data science work to build skills.
For data engineering, it’s strongly recommended that you start a cloud account in Google Cloud, AWS and Azure. They offer “pay-as-you-go” options and are subscription based services based on the amount of compute time you accumulate. And with the many of the open data sets available free to the public, you can easily build test data pipelines in the cloud on your free time. You can also build pipelines in the cloud to help with you current DBA role. Most companies are transitioning to the cloud and offer their employees cloud access.
Post-graduate education is another path DBAs can take. There are many post-graduate and certificate programs in data science and big data engineering, with many more coming online. And these programs are flexible enough where you can learn outside your normal work hours.
Recently I’ve been tasked with analyzing Biological and Genomic data. I’ve learned a lot about tools and libraries for R and Python. As part of this analysis, I’m helping scientists analyze genome variations and perform analysis of genotypes. The human genome has 23 chromosomes. That’s about 3 billion base pairs that contain around 30,000 genes. Every base has pair that can be coded with 2 bits. This equates to around 750 megabytes of data. The data that I have been analyzing is several terabytes of genome sequences for around eight humans. Because the data is so massive, there are several high-throughput tools available to perform genotyping and variation discovery that I will cover in a series of articles in the next few months.
One characteristic is that repetitive DNA sequences comprise approximately 50% of the human genome. Genome size 3,100 Mbps (mega-basepairs) per haploid genome. A base pair is two chemical bases bonded to one another forming the “rung” in the DNA. DNA strands look someone like ladder twisted around.
Variations
Variations include differences in the number of copies individuals have of a particular gene, deletions, translocations and inversions. One such variation is Single-nucleotide polymorphism (SNPs). It’s a type of copy number variation (CNV), Variations in DNA are actually a normal part of human genetics and can sometimes be a sign of the body adapting to various changes within the sequences or even adaptation for protecting and adapting.
SNP can be any nucleic acid substitution:
Transition
Interchange of the purine (Adenine/Guanine)
Pyrimidine (Cytosine/Thymine) nucleic acids
Transversion
Interchange of purine and pyrimidine nucleic acid
Since variation discovery is very important in the biological sciences, many tools have been developed to assist in creating medicines and treatments for all type of mutations within cells.
The International HapMap Project was develop a describe of variation patterns in the human genome that finds variations that impact health, responses to drugs and an individual’s environment. Variations include small-scale and large-scale variations.
Copy number variation (CNV). With the number of copies of a particular gene varies from one individual to the next. Following the completion of he Human Genome Project, it became apparent that the genome experiences gains and losses of genetic material. The extent to which copy number variation contributes to human disease is not yet known. It has long been recognized that some cancers are associated with elevated copy numbers of particular genes. They are categorized as long repeats or short repeats.
Insertions and Deletions (InDel) are a type of CNV: Insertion-deletion mutations refer to insertion and/or deletion of nucleotides into genomic DNA and include events less that 1Kb in length.
Other Definitions
Length of the base pairs (bp). One bp corresponds to approximately 3.4 A (340 pm) of length along the strand, and to roughly 618 or 643 daltons for DNA and RNA respectively.
Kilobase (kb) is a unit of measurement in molecular biology equal to 1000 base pairs of DNA or RNA.
Data Analysis
Most of analysis is performed in R. Here are some of the analysis done using Genome libraries:
The above libraries are standard R libraries for analyzing Genomic data. Later in this document, I will discuss the multiple tools that produce the files necessary for these libraries.
The most advanced libraries can be downloaded from the BiocManager website.
if (!require("BiocManager", quietly = TRUE))
install.packages("BiocManager")
BiocManager::install()
if (!requireNamespace("BiocManager", quietly = TRUE))
install.packages("BiocManager")
BiocManager::install("Rsamtools")
BiocManager::install("pasillaBamSubset")
Visualization
Function
Patient1A
Using R with Human Genome Variation Data
Reading VCF files into R.
The vcfR package was designed to work with data from VCF files. The vcfR package was designed to work on an individual chromosome. A VCF file structure is a standard file format for storing variations for genomic data and is used by organizations to map human genome variations. It used used for large scale variant mapping. One example is the International Genome Sample Resource (IGSR).
It contains headers
CHROM
POS
ID
REF
ALT
QUAL
FILTER
INFO
FORMAT
The name of the chromosome.
The starting position of the variant indicated.
Identifier
Reference allele. An allele is one of two or more alternative forms of a gene that occur by mutation and found in the same area of a chromosome.
Alternate allele
Quality score out of 100.
Pass/Fail. Did it pace quality filters.
Information about the following columns.
Format of the columns.
FASTQ file format
The FASTQ files contain entire genome sequencing and can be very large and represents the raw sequencing data.
BAM or CRAM file formats
These are the files that align sequencing data with referencing genome data.
Genomics Tools
Genome data is very large, and contains millions of base pairs for chromosomes. Although this data can be loaded into R, the complexity of looking at individual genes and chromosomes can be very daunting. One tool that makes reading genomic data more visual is Integrative Genomics Viewer or (IGV). IVG is a visualization tool that zooms in to the gene and chromosome level at the base length.
IGV efficiently pulls in BAM file indexes to locate genomic data.
Other tools for Genomics, structural biology and molecular biology is DNASTAR Lasergene Structural Biology Suite and Spartan.
Another tool for visualization is the Variant Effect Predictor (VEP), which determines the effect of variants on genes.
Other tools include SnpEff and SnpSuft. SnpEff provides genetic variant annotation and function effect prediction. It also annotates and predicts the effect of genetic variants on genetic variants on genes and protein.
SnpSift annotates genomic variants using database, filters, and annotated variants. Once you annotated your files using SnpEff, you can use SnpFift to help you filter large genomic datasets in order to find the most significant variants for your experiment. Microsoft Genomics: All SnpEff & SnpSift genomic database are kindly hosted by Microsoft Genomics and Azure
Microsoft Genomics service provides a cloud hosted solution that makes it easy to variant call your genomic samples. The service takes in genomic samples as two paired end read fastq (.fq.gz) files and produces .bam, .bai, or.vcf files, along with the associated log files.
The process uses a BWA / GATK data pipeline where Microsoft has improve the efficiency of both BWA and GATK producing results faster and with less overhead. There is also a secondary analysis .
GATK is the Genome Analysis Toolkit also used for variant discovery using a data pipeline which can be scaled in the Azure or Google cloud. GATK is a framework for Variant Discovery with high-throughput sequencing data.
Another tool is the CNVnator is a tool for CNV discovery and genotyping from depth-of-coverage by mapped reads
To ensure optimal performance of the database, an administrator must follow the most important database areas to maintenance including:
Rebuilding indexes
Minimizing procedure compilations and recompilations during heavy workloads.
Check page allocation, contention and aging.
Actions such as running the re-indexing script daily and checking for fragmentation are important for optimization health.
Plan and SQL handles
Optimization of code to reduce the amount of logical and physical lookups occurring in memory and disk should be the first method of troubleshooting performance issues. When code has been released into a production environment, it is not always possible to change code to make it faster. At times, what is needed is to monitor for plan changes and plan execution. As part of this effort, it’s important to ensure that plans executed on the database maintain a consistent optimal execution plan or that no significant plan execution change occur. In the Appendix, there are queries that will all an administrator observe plan changes and execution statistics. Here is an example of how to investigate plan stability in a SQL-Server database. The table below is a typical query used multiple times during the day with its respective plan handle which is a hash of the query plan. You can map a particular SQL text to a plan handle using the dynamic management function (DMF) sys.dm_exec_sql_text(sql_handle | plan_handle).
SQL Statement
Plan Handle
SELECT * FROM Sales.SalesOrderHeader AS h, Sales.Customer AS c, Sales.SalesTerritory AS t WHERE h.CustomerID = c.CustomerID AND c.TerritoryID = t.TerritoryID AND CountryRegionCode = @Country_region
Having multiple plan handles is not necessarily an issue and doesn’t mean the plan is running errantly. Investigation of the query plan can help determine if the plan has a high cost to the optimizer.
Steps necessary to determine if query execution is optimized includes
Looking into the plan cache to determine cache plan reuse is occurring.
Monitor for multiple compilations and recompilation to make sure it is minimized and preplanned.
Report any issues with long running code to Itron Support.
Checking for locking issues such has long PAGELATCHIO latch waits and deadlocks are critical. Administrators must check for deadlock events either by running traces or dynamic management views.
In the appendix below, there are examples of looking for specific plan handle performance and the use of plan guides. Detail of this methods are beyond the scope of this report and should be researched and thoroughly tested before use.
Plan Maintenance Analysis Queries
SET NOCOUNT ON
GO
/* Query checks for memory usage in database o/s */
SELECT
(physical_memory_in_use_kb/1024.0/1024.0) AS Memory_usedby_Sqlserver_GB,
(locked_page_allocations_kb/1024.0) AS Locked_pages_used_Sqlserver_MB,
(total_virtual_address_space_kb/1024.0/1024.0) AS Total_VAS_in_GB,
process_physical_memory_low,
process_virtual_memory_low
FROM sys.dm_os_process_memory;
SELECT object_name, cntr_value
FROM sys.dm_os_performance_counters
WHERE counter_name IN ('Total Server Memory (KB)', 'Target Server Memory (KB)');
SELECT physical_memory_kb FROM sys.dm_os_sys_info;
SELECT physical_memory_in_bytes FROM sys.dm_os_sys_info;
SELECT top(5) sum(total_physical_reads) tot_prds, sum(max_physical_reads) tot_max_prds, sum(total_logical_reads) tot_lrds, sum(max_logical_reads) tot_max_lrds,
sum(total_logical_writes) tot_lwrts, sum(max_logical_writes) tot_max_lwrts
FROM sys.dm_exec_query_stats stat
GO
SELECT usecounts, size_in_bytes, cacheobjtype,
SUM(total_worker_time / 1000) AS total_cpu_time_in_ms,
SUM(total_physical_reads) AS total_physical_reads,
SUM(total_logical_reads) AS total_logical_reads,
SUM(total_logical_writes) AS total_logical_write,
REPLACE (REPLACE([text], char(13), ' '), CHAR(10), ' ') AS sql_text
FROM sys.dm_exec_cached_plans AS p
INNER JOIN sys.dm_exec_query_stats stat ON p.plan_handle = stat.plan_handle
CROSS APPLY sys.dm_exec_sql_text (p.plan_handle)
WHERE p.objtype = 'Proc' AND cacheobjtype = 'Compiled Plan'
GROUP BY usecounts, size_in_bytes, cacheobjtype, [text]
ORDER BY usecounts DESC, total_logical_reads DESC, total_logical_write DESC
GO
SELECT usecounts, size_in_bytes, cacheobjtype,
SUM(total_worker_time / 1000) AS total_cpu_time_in_ms,
SUM(total_physical_reads) AS total_physical_reads,
SUM(total_logical_reads) AS total_logical_reads,
SUM(total_logical_writes) AS total_logical_write,
p.plan_handle,
REPLACE (REPLACE([text], char(13), ' '), CHAR(10), ' ') AS sql_text
FROM sys.dm_exec_cached_plans AS p
INNER JOIN sys.dm_exec_query_stats stat ON p.plan_handle = stat.plan_handle
CROSS APPLY sys.dm_exec_sql_text (p.plan_handle)
WHERE p.objtype = 'Proc' AND cacheobjtype = 'Compiled Plan'
GROUP BY usecounts, size_in_bytes, cacheobjtype, [text], p.plan_handle
ORDER BY usecounts DESC, total_logical_reads DESC, total_logical_write DESC
GO
/* Can use query to check for specific plan handles based on performance */
SELECT usecounts, size_in_bytes, cacheobjtype,
SUM(total_worker_time / 1000) AS total_cpu_time_in_ms,
SUM(total_physical_reads) AS total_physical_reads,
SUM(total_logical_reads) AS total_logical_reads,
SUM(total_logical_writes) AS total_logical_write,
p.plan_handle
REPLACE (REPLACE([text], char(13), ' '), CHAR(10), ' ') AS sql_text
FROM sys.dm_exec_cached_plans AS p
INNER JOIN sys.dm_exec_query_stats stat ON p.plan_handle = stat.plan_handle
CROSS APPLY sys.dm_exec_sql_text (0x050005007E58905A307BC1EB1800000001000000000000000000000000000000000000000000000000000000)
WHERE p.objtype = 'Proc' AND cacheobjtype = 'Compiled Plan'
GROUP BY usecounts, size_in_bytes, cacheobjtype, [text], p.plan_handle
ORDER BY usecounts DESC, total_logical_reads DESC, total_logical_write DESC
GO
select * from sys.dm_exec_cached_plan_dependent_objects(0x050005007E58905A307BC1EB1800000001000000000000000000000000000000000000000000000000000000)
go
sp_create_plan_guide_from handle
go
SELECT TOP(10) total_physical_reads, last_physical_reads, min_physical_reads, max_physical_reads,
min_physical_reads, max_physical_reads, total_logical_writes, last_logical_writes,
min_logical_writes, max_logical_writes, total_logical_reads, last_logical_reads,
min_logical_reads, max_logical_reads,
REPLACE (REPLACE([text], char(13), ' '), CHAR(10), ' ') AS sql_text
FROM sys.dm_exec_cached_plans AS p
INNER JOIN sys.dm_exec_query_stats stat ON p.plan_handle = stat.plan_handle
CROSS APPLY sys.dm_exec_sql_text (stat.sql_handle)
ORDER BY total_physical_reads, Total_logical_reads DESC
GO
SELECT TOP(10) total_physical_reads, max_physical_reads, total_logical_writes, max_logical_writes,
REPLACE (REPLACE([text], char(13), ' '), CHAR(10), ' ') AS sql_text
FROM sys.dm_exec_cached_plans AS p
INNER JOIN sys.dm_exec_query_stats stat ON p.plan_handle = stat.plan_handle
CROSS APPLY sys.dm_exec_sql_text (stat.sql_handle)
WHERE p.objtype <> 'Proc'
ORDER BY total_physical_reads, Total_logical_reads DESC
GO
SELECT t1.session_id, t1.request_id, t1.task_alloc,
t1.task_dealloc, t2.statement_start_offset,
t2.statement_end_offset, REPLACE (REPLACE([text], char(13), ' '), CHAR(10), ' ') AS sql_text
FROM (Select session_id, request_id,
SUM(internal_objects_alloc_page_count) AS task_alloc,
SUM (internal_objects_dealloc_page_count) AS task_dealloc
FROM sys.dm_db_task_space_usage
GROUP BY session_id, request_id) AS t1,
sys.dm_exec_requests AS t2
INNER JOIN sys.dm_exec_query_stats stat ON t2.plan_handle = stat.plan_handle
CROSS APPLY sys.dm_exec_sql_text (stat.sql_handle)
WHERE t1.session_id = t2.session_id
AND (t1.request_id = t2.request_id)
-- I/O query stats based on the sql text
SELECT top (10) (stats.total_logical_reads/stats.execution_count),
(stats.total_logical_writes/stats.execution_count),
(stats.total_physical_reads/stats.execution_count),
stats.execution_count, stats.sql_handle, stats.plan_handle,
REPLACE (REPLACE([text], char(13), ' '), CHAR(10), ' ') AS sql_text
FROM sys.dm_exec_query_stats stats
CROSS APPLY sys.dm_exec_sql_text (stats.sql_handle)
ORDER BY (total_logical_reads + total_logical_writes) DESC
-- Missed Index information
select TOP(50) * from sys.dm_db_missing_index_group_stats
GO
select object_name(object_id) object, equality_columns, included_columns, statement from sys.dm_db_missing_index_details
go
/* Queries below use an option technique known as plan guides */
sp_create_plan_guide_from_handle @name = N'plan_guide_name'
-- Create a plan guide for the query by specifying the query plan in the plan cache.
DECLARE @plan_handle varbinary(64);
DECLARE @offset int;
SELECT @plan_handle = plan_handle, @offset = qs.statement_start_offset
FROM sys.dm_exec_query_stats AS qs
CROSS APPLY sys.dm_exec_sql_text(sql_handle) AS st
CROSS APPLY sys.dm_exec_text_query_plan(qs.plan_handle, qs.statement_start_offset, qs.statement_end_offset) AS qp
WHERE text LIKE N'SELECT WorkOrderID, p.Name, OrderQty, DueDate%';
EXECUTE sp_create_plan_guide_from_handle
@name = N'Guide1',
@plan_handle = @plan_handle,
@statement_start_offset = @offset;
GO
-- Verify that the plan guide is created.
SELECT * FROM sys.plan_guides
WHERE scope_batch LIKE N'SELECT WorkOrderID, p.Name, OrderQty, DueDate%';
GO
Create Plan Guides in SQL-Server
sp_create_plan_guide
@name = N'Guide1',
@stmt = N'SELECT * FROM Sales.SalesOrderHeader AS h,
Sales.Customer AS c,
Sales.SalesTerritory AS t
WHERE h.CustomerID = c.CustomerID
AND c.TerritoryID = t.TerritoryID
AND CountryRegionCode = @Country_region',
@type = N'OBJECT',
@module_or_batch = N'Sales.GetSalesOrderByCountry',
@params = NULL,
@hints = N'OPTION (OPTIMIZE FOR (@Country_region = N''US''))'
Query Plan Stability ensures predictable and appreciable database performance no matter how much data is being stored in the buffer cache or on disk. It ensures that all queries are performing according to business requirements and processes are running in a timely manner during the all business hours.
The information presented in this document applies to object relational databases with a cost-base optimizer. The principal audience for this documentation are database administrators, database programmers and customer support analyst.
Whenever confronted with a poorly performing application. The following typically occurs during troubleshooting
Ask stakeholder when and at what frequency statistical collection is performed. If stakeholder has not computed statistics recently or has never computed statistics, they must compute statistics before proceeding.
Ask customers if there has been a recent change in data. If this has occurred, get as much detail on the changes
When and where the changes made
The quantity of changes.
During execution of processes plan instability can occur due to the following factors:
Lack of adherence to cardinality and primary and foreign key relationships.
Lack of proper statistics.
Misuse of predicates in query and plan binding.
Flush of “good” plans from the shared pool (plan cache).
One of the best tools for ensuring plan stability in Oracle is the cost-based optimizer explain plan, which helps determine how costly it is to execute a plan based on its cost in CPU.
Query identifies in Oracle (SQL_ID) are indexes with alphanumeric characters (e.g. 3mx8whn1c5jbb).
When reviewing query execution performance, it’s always best to create a query plan:
SQL>EXPLAIN PLAN FOR
select XML_LOADID, XML_RECORDTEXT FROM OLAPSYS.XML_LOAD_RECORDS WHERE XML_RECORDID=2;
SQL> select * from TABLE(DBMS_XPLAN.DISPLAY);
Explain plans show how the query is performing in the cost-based optimizer once parsed. It provides valuable information of where the highest cost are in your query. Query tuning is essential for maintaining performance in a cost-based optimizer.
If plan instability occurs in an Oracle database, there are several options in addition to the list in the preceding sections to correct the issue.
Query performs very poorly or performs full table scans on very high cardinal and big table objects.
Make sure that statistical collection script has been executed. Make certain that statistics are up to date. See appendix for script to check statistics.
If Statistics are up to date. Attempt to generate a plan analysis (SQL profile) of the current plan. Note: Oracle Diagnostic Pack and Automated Database Diagnostic Manager (ADDM) needs to be installed. The profile can be generated via the OEM GUI or using scripts.
The following steps allow an administrator to create SQL profile tuning sets as well as export out those profiles from a source database and import it into a new database. This allows administrator to create and test better plans in test systems and then load them safely into production systems and enable/disable them when needed.
SET HEADING ON
SET PAGESIZE 20000
SET LINESIZE 2000
COL text FOR A50
COL ctext FOR A50
select vs.last_load_time, ao.OWNER, parsing_schema_name, first_load_time , ao.OBJECT_NAME, vs.program_line#, executions exe, vs.sqltype, vs.sql_id, vs.rows_processed rows_processed, concurrency_wait_time, elapsed_time/1000000 elapsed_secs, elapsed_time/1000000/(case when executions = 0 then 1 else executions end) elap_per_exec_secs, vs.sql_fulltext text, vs.sql_text ctext
from v$sql vs, all_objects ao
where vs.PROGRAM_ID = ao.OBJECT_ID and parsing_schema_name not in ('SYS','SYSTEM') and parsing_schema_name in ('<SCHEMA_OWNER>')
and owner not in ('SYS','SYSTEM','DBSNMP','SYSMAN','MDSYS')
order by vs.last_load_time desc , vs.parsing_schema_name, vs.first_load_time desc , program_id, vs.program_line#;
select address, hash_value, plan_hash_value from v$sqlarea where sql_id in ('2zd224kurqsr9');
ADDRESS HASH_VALUE PLAN_HASH_VALUE
---------------- ---------- ---------------
00000003ACC32290 3419553494 1111780545
Prior to doing a purge of a PLAN_HASH from the shared_pool, it’s important to collect information about the bad plan. You can do this by executing an DBMS_XPLAN outline on the Plans. To preserve the plan prior to flushing if from the shared_pool, read section on Loading Plan from Cache to Baseline and return here to continue.
SQL> EXPLAIN PLAN FOR select XML_LOADID, XML_RECORDTEXT FROM OLAPSYS.XML_LOAD_RECORDS WHERE XML_RECORDID=2;
Explained.
SQL> select * from TABLE(DBMS_XPLAN.DISPLAY);
If plan exists in memory, but has a bad hash plan number, create tuning task and SQL set for the query.
Execute tuning task command to see if ADDM will generate a better plan (Do not purge from memory if using this step).
var stmt_task VARCHAR2(64);
SET SERVEROUTPUT ON LINESIZE 200 PAGESIZE 20000 LONG 9999
EXEC :stmt_task := DBMS_SQLTUNE.CREATE_TUNING_TASK(sql_id => '2zd224kurqsr9', task_name => 'sga_tuning_task_1');
SELECT DBMS_SQLTUNE.REPORT_TUNING_TASK('sga_tuning_task_1', 'TEXT', 'TYPICAL', 'FINDINGS') FROM DUAL;
If no results are returned, then ADDM will not be able to tune.
SQL> SELECT DBMS_SQLTUNE.REPORT_TUNING_TASK('sga_tuning_task_1', 'TEXT', 'TYPICAL', 'FINDINGS') FROM DUAL;
ERROR:
ORA-13631: The most recent execution of task sga_tuning_task_1 contains no results.
ORA-06512: at "SYS.PRVT_ADVISOR", line 5739
ORA-06512: at "SYS.DBMS_SQLTUNE", line 1045
ORA-06512: at line 1
If no results are returned skip following query and go to step 6. Always make sure not to purge SGA if you use these steps.
Find the begin and end span for the SQL_ID and plan hash that you need from AWR (This is if the plan has been purged from the pool and exists in AWR repository.
SET LINESIZE 2000 PAGESIZE 20000
SET LONG 99999
select
SNAP_ID,
TO_CHAR(begin_interval_time,'DD-MON-YYYY HH24') begin_interval_time,
TO_CHAR(end_interval_time,'DD-MON-YYYY HH24') end_interval_time,
SQL_ID,
round((round((avg(ELAPSED_TIME_DELTA)/1000000),2)/(case when avg(EXECUTIONS_DELTA)=0 then 1 else avg(EXECUTIONS_DELTA) end)),2) as ELAPSED_TIME_SECS,
round((round((avg(CPU_TIME_DELTA)/1000000),2)/(case when avg(EXECUTIONS_DELTA)=0 then 1 else avg(EXECUTIONS_DELTA) end)),2) as CPU_TIME_SECS,
round((avg(BUFFER_GETS_DELTA)/(case when avg(EXECUTIONS_DELTA)=0 then 1 else avg(EXECUTIONS_DELTA) end)),2) as GETS_PER_EXEC
from
dba_hist_snapshot natural join dba_hist_sqlstat natural join dba_hist_sqltext
where
(elapsed_time_delta > 0 or elapsed_time_delta is not null)
and SQL_ID = 'bbuc9hr5x4gqq'
group by
SNAP_ID,
TO_CHAR(begin_interval_time,'DD-MON-YYYY HH24'),
TO_CHAR(end_interval_time,'DD-MON-YYYY HH24'),
SQL_ID
order by
snap_id asc
/
Create a SQL set.
Begin
DBMS_SQLTUNE.CREATE_SQLSET (sqlset_name => '2zd224kurqsr9_TUNING_SET_1');
END;
/
Load SQL Tuning Set.
DECLARE
Cur sys_refcursor;
BEGIN
OPEN cur FOR
SELECT VALUE(P) FROM TABLE(dbms_sqltune.select_workload_repository(begin_snap=>13645, end_snap=>13649, Basic_filter=>'sql_id=''2zd224kurqsr9''', attribute_list => 'ALL' )
) p;
DBMS_SQLTUNE.LOAD_SQLSET(sqlset_name=> '2zd224kurqsr9_TUNING_SET_1', populate_cursor=> cur);
CLOSE cur;
End;
/
Verify tuning set is correct.
SELECT * FROM TABLE(DBMS_SQLTUNE.SELECT_SQLSET(sqlset_name => '2zd224kurqsr9_TUNING_SET_1'));
create the sql set staging table (Cannot be created in the SYS or SYSTEM schema).
Check the count of the table to make sure it’s been populated.
SQL> select count(*) from <SCHEMA_OWNER_SOURCE>.TUNING_SET_1_STGTAB;
COUNT(*)
----------
3
Export out the staging table.
[oracle]$ expdp system/******* DUMPFILE=TUNIING_SET_1.DMP DIRECTORY=BACKUPS TABLES='<SCHEMA_OWNER_SOURCE>.TUNING_SET_1_STGTAB'
Export: Release 11.2.0.4.0 - Production on Fri Mar 9 04:10:34 2018
Copyright (c) 1982, 2011, Oracle and/or its affiliates. All rights reserved.
Connected to: Oracle Database 12c Enterprise Edition Release 12.1.0.2.0 - 64bit Production
With the Partitioning, OLAP, Advanced Analytics and Real Application Testing options
Starting "SYSTEM"."SYS_EXPORT_TABLE_01": system/******** DUMPFILE=TUNIING_SET_1.DMP DIRECTORY=BACKUPS TABLES=<SCHEMA_OWNER_SOURCE>.TUNING_SET_1_STGTAB
Estimate in progress using BLOCKS method...
Processing object type TABLE_EXPORT/TABLE/TABLE_DATA
Total estimation using BLOCKS method: 9.562 MB
Processing object type TABLE_EXPORT/TABLE/TABLE
Processing object type TABLE_EXPORT/TABLE/INDEX/STATISTICS/INDEX_STATISTICS
Processing object type TABLE_EXPORT/TABLE/STATISTICS/TABLE_STATISTICS
Processing object type TABLE_EXPORT/TABLE/STATISTICS/MARKER
. . exported "<SCHEMA_OWNER_SOURCE>"."TUNING_SET_1_STGTAB" 54.01 KB 3 rows
Master table "SYSTEM"."SYS_EXPORT_TABLE_01" successfully loaded/unloaded
******************************************************************************
Dump file set for SYSTEM.SYS_EXPORT_TABLE_01 is:
/data/backups/TUNIING_SET_1.DMP
Job "SYSTEM"."SYS_EXPORT_TABLE_01" successfully completed at Fri Mar 9 04:11:10 2018 elapsed 0 00:00:32
******** impdp staging table into target database ******
Connected to: Oracle Database 12c Enterprise Edition Release 12.2.0.1.0 - 64bit Production
Master table "SYSTEM"."SYS_IMPORT_FULL_01" successfully loaded/unloaded
Starting "SYSTEM"."SYS_IMPORT_FULL_01": system/******** DUMPFILE=TUNIING_SET_1.DMP REMAP_SCHEMA=<schema_owner_source>:<schema_owner> DIRECTORY=BACKUPS
Processing object type TABLE_EXPORT/TABLE/TABLE
Processing object type TABLE_EXPORT/TABLE/TABLE_DATA
. . imported "<SCHEMA_OWNER>"."TUNING_SET_1_STGTAB" 54.01 KB 3 rows
Processing object type TABLE_EXPORT/TABLE/INDEX/STATISTICS/INDEX_STATISTICS
Processing object type TABLE_EXPORT/TABLE/STATISTICS/TABLE_STATISTICS
Processing object type TABLE_EXPORT/TABLE/STATISTICS/MARKER
Job "SYSTEM"."SYS_IMPORT_FULL_01" successfully completed at Fri Mar 9 04:29:52 2018 elapsed 0 00:00:41
Purge the plan from the shared pool on source database.
exec sys.dbms_shared_pool.purge('00000003ACC32290,3419553494','C');
*** OR ***
set pagesize 20000
select 'exec sys.dbms_shared_pool.purge(''' || address || ',' || hash_value || ''',''C'');' from v$sqlarea where sql_text like '%TASKTEMPLATEPARAMETERVALUE X where (1=1)%'
/
'EXECSYS.DBMS_SHARED_POOL.PURGE('''||ADDRESS||','||HASH_VALUE||''',''C'');'
--------------------------------------------------------------------------------
exec sys.dbms_shared_pool.purge('00000003ACC32290,3419553494','C');
exec sys.dbms_shared_pool.purge('0000000127D41C68,3957004154','C');
exec sys.dbms_shared_pool.purge('00000001A851BB70,525044174','C');
exec sys.dbms_shared_pool.purge('000000016C757A98,4128744307','C');
exec sys.dbms_shared_pool.purge('000000025115E2A8,4132567071','C');
Installing new plan on target database.
Unpack the SQL set in the target database.
NAME
--------------------------------------------------------------------------------
CREATED STATEMENT_COUNT
------------------- ---------------
bbuc9hr5x4gqq_TUNING_SET_1
2018-03-09 04:33:59
Load plan into SQL Plan Management (SPM).
set serveroutput on
declare
my_integer pls_integer;
begin
my_integer := dbms_spm.load_plans_from_sqlset (
sqlset_name => '2zd224kurqsr9_TUNING_SET_1',
sqlset_owner => 'SYS',
fixed => 'YES',
enabled => 'YES'
);
DBMS_OUTPUT.PUT_line(my_integer);
end;
/
Select sql_id, exact_matching_signature, force_matching_signature from v$sql where sql_text like ‘%<sql_text%’;
Create baseline from plan.
SET SERVEROUTPUT ON
declare
my_int pls_integer;
begin
my_int := DBMS_SPM.load_plans_from_cursor_cache(sql_id => '2zd224kurqsr9’, plan_hash_value => 1111780545, fixed => 'NO', enabled => 'NO');
DBMS_OUTPUT.PUT_line(my_int);
end;
/
List baseline to make sure it has been loaded.
SELECT * FROM dba_sql_plan_baselines where signature=<exact matching signature query>;
Make sure to load current plan from cursor cache into baseline and disable with the following command. Also make certain that the baseline is not accepted.
The Great Recession was one of the most turbulent economic periods of the past eighty years. It was a global economic recession that impacted hundreds of banks, some of them responsible for financing the Gross Domestic Product (GDP) of entire countries. During the recession, many banks closed due to the speculation that flooded into the real estate market with new banking products that gave loans to millions of subprime consumers. This allowed people to take out loans with low interest rates but very complicated terms that made it much easier to end up in foreclosure proceedings. During this period, home mortgages defaults skyrocketed in many states further depressing the market. This in turned caused many people to lose their life savings as well as their home and jobs. It is now popularly considered the longest period of economic downturn since the Great Depression of the 1930’s.
Since the great recession, many financial regulations and policies were put in place to prevent it from happening in the future. The most popular of these were the Dodd-Frank Wall Street Reform and Consumer Protection act, also known as part of the Emergency Economic Stabilization Act, passed by Congress that amended many existing regulations to make it much easier to protect consumers by creating new government agents tasked with overseeing aspects of the financial banking system. When Donald Trump was elected President in 2016, he signed a new law rolling back significant portions of the law.
One of the upsides of the recession is how much articles, books, and analysis done before, during and after the financial crisis. This is of significant importance, because understanding how the financial markets got to that point in 2008, will help consumers better understand and better prepare for what not to do. Another added benefit of understanding this period of time, is how many banks gambled with risky financial products, only to lose all the money it had. Many consumers are now educated enough to know take on these risky loans, and banks scrutinized mortgage applications more closely. During the recession, Inflation in the market ballooned housing prices until there was an inevitable crash.
The following report details state-by-state the impact of this period on the housing market, consumers, and overall housing values to give the audience a better understanding of quantitative impact monthly and yearly. I will also show visualizations of housing prices detailing the loss of housing value, as a result causing many borrowers to be “under water” with their home mortgages. The report will also focus on four states (North Carolina, California, Massachusetts and Florida) and impact on job losses and employment each month during the period of this recession.
Charts and Graphs
One the most crippling results of the Great Recession was on consumers. Many consumers lost their homes as the downturn rippled throughout the country. Figure 1 shows an aggregate picture of housing prices between 1996 and 2017 for the four states analyzed. Notice how there was a steep growth in housing values and then a sudden drop during the period during and shortly after the recession. Housing values would eventually rise again, but trillions of dollars of equity would be lost, with many communities not recovering.
Figure (1): Average condo home prices in Florida and California were impacted more heavily by the economic downturn and drop in housing prices compared to North Carolina and Massachusetts. Source Zillow.com
The impact of housing prices for California and Florida do not really come as a surprise. Both of these states tend to have housing values greater than states where the cost of living is less. Also, these states tend to have residents with higher incomes than the general population (retirees and white-collar workers).
When compared to the entire country, several states saw changes in the percentage of income compared to the change in home ownership. This is an indication of how well some states weathered the economic downturn among their populations. States such as California, Nevada, and many areas in the southwest saw a slow precipitous drop in home ownership along with a drop in income (with the exception of Utah). Many states in the south did see drops in home ownership, but on average, the incomes of their populations remained the same. North Carolina, for instance, saw no net loss of income, but an increase in home ownership. States such as Nevada saw both large losses in income for their population as well as loss in home ownership in Figure 2. Nevada was particularly hit hard by the economic recession.
Figure (2): A heat map of the country comparing changes in income and home ownership. Source GeoFred. https://geofred.stlouisfed.org/
The nest visualization shows the average unemployment rate. This increased significantly during and after the great recession. In figure 3, it shows how this unemployment became more long than the period of the recession itself, showing the economic impact on families beyond the initial wave of economic decline.
What these graphs show us is how, during the economic downturn, there was not only an impact on the housing market, but also income growth and unemployment. Showing the scope and depth of the problem. One of the unfortunate results of the recession was that many banks considered “too big to fail” received government funding to bail them out, and many homeowners and consumers were left to fill the blunt of the economic recession on their own.
The R language has a number of machine learning libraries to help determine for both supervised and unsupervised machine learning. This includes such ML techniques such as linear and logistic regression, decision trees, random forest, generalized boosted regression modeling among others. I strongly recommend learning how these models work and how they can be used to predictive analytics.
Part of the Machine Learning process includes the following:
Sample: Create a sample set of data either through random sampling or top tier sampling. Create a test, training and validation set of data.
Explore: Use exploratory methods on the data. This includes descriptive statistics, scatter plots, histograms, etc.
Modify: Clean, prepare, impute or filter data. Perform cluster analysis, association and segmentation.
Model: Model the data using Logistic or Linear regression, Neural Networking, and Decision Trees.
Assess: Access the model by comparing it to other model types and again real data. Determine how close your model is to reality. Test the data using hypothesis testing.
When creating machine learning models for any application, it is wise to following a process flow such as the following:
In the following example, we use machine learning to determine the credit worthiness of prospective borrowers for a bank loan.
The loan data consist of the following inputs
Loan amount
Interest rate
Grade of credit
Employment length of borrower
Home ownership status
Annual Income
Age of borrower
The response variable or predictor to predict the default rate
Loan status (0 or 1).
After loading the data into R, we partition the data for training or testing sets.
loan <- read.csv("loan.csv", stringsAsFactors = TRUE)
str(loan)
## Split the data into 70% training and 30% test datasets
library(rsample)
set.seed(634)
loan_split <- initial_split(loan, prop = 0.7)
loan_training <- training(loan_split)
loan_test <- testing(loan_split)
Create a over-sample training data based on ROSE library. This checks for over-sampling of the data.
str(loan_training)
table(loan_training$loan_status)
library(ROSE)
loan_training_both <- ovun.sample(loan_status ~ ., data = loan_training, method = "both", p = 0.5)$data
table(loan_training_both$loan_status)
Build a logistic regression model and a classification tree to predict loan default.
loan_logistic <- glm(loan_status ~ . , data = loan_training_both, family = "binomial")
library(rpart)
loan_ctree <- rpart(loan_status ~ . , data = loan_training_both, method = "class")
library(rpart.plot)
rpart.plot(loan_ctree, cex=1)
Build the ensemble models (random forest, gradient boosting) to predict loan default.
loan_gbm <- gbm(loan_status ~ ., data = loan_training_both, n.trees = 200, distribution = "bernoulli")
summary(loan_gbm)
Use the ROC (receiver operating curve) and compute the AUC (area under the curve) to check the specificity and sensitivity of the models.
# Step 1. Predicting on test data
predicted_logistic <- loan_logistic %>%
predict(newdata = loan_test, type = "response")
predicted_ctree <- loan_ctree %>%
predict(newdata = loan_test, type = "prob")
predicted_rf <- loan_rf %>%
predict(newdata = loan_test, type = "prob")
predicted_gbm <- loan_gbm %>%
predict(newdata = loan_test, type = "response")
# Step 3. Create ROC and Compute AUC
library(cutpointr)
roc_logistic <- roc(loan_test, x= .fitted_logistic, class = loan_status, pos_class = 1 , neg_class = 0)
roc_ctree<- roc(loan_test, x= .fitted_ctree, class = loan_status, pos_class = 1 , neg_class = 0)
roc_rf<- roc(loan_test, x= .fitted_rf, class = loan_status, pos_class = 1 , neg_class = 0)
roc_gbm<- roc(loan_test, x= .fitted_gbm, class = loan_status, pos_class = 1 , neg_class = 0)
plot(roc_logistic) +
geom_line(data = roc_logistic, color = "red") +
geom_line(data = roc_ctree, color = "blue") +
geom_line(data = roc_rf, color = "green") +
geom_line(data = roc_gbm, color = "black")
auc(roc_logistic)
auc(roc_ctree)
auc(roc_rf)
auc(roc_gbm)
These help you compare and score which model works best for the type of data presented in the test set. When looking at the ROC chart, you can see that the gradient boost model has the best performance of all the model as it is closer to 1.00 than the other models. Classifiers that are closer to 1.00 for the top left where Sensitivity is 1.00 and Specificity is closer to 0.00 have the best performance.
