Recently, on irc, there have been some talks with people using various pg_dump/pg_dumpall calls to get dumps of database.
I voiced my ideas, but figured it could be good subject for a blog post.
Continue reading How to efficiently dump PostgreSQL databases
Just pushed new version of explain.depesz.com site.
Changes:
On 19th of November 2019, Thomas Munro committed patch:
Allow invisible PROMPT2 in psql. Keep track of the visible width of PROMPT1, and provide %w as a way for PROMPT2 to generate the same number of spaces. Author: Thomas Munro, with ideas from others Discussion: https://postgr.es/m/CA%2BhUKG%2BzGd7RigjWbxwhzGW59gUpf76ydQECeGdEdodH6nd__A%40mail.gmail.com
Continue reading Waiting for PostgreSQL 13 – Allow invisible PROMPT2 in psql.
On 13rd of November 2019, Amit Kapila committed patch:
Introduce the 'force' option for the Drop Database command. This new option terminates the other sessions connected to the target database and then drop it. To terminate other sessions, the current user must have desired permissions (same as pg_terminate_backend()). We don't allow to terminate the sessions if prepared transactions, active logical replication slots or subscriptions are present in the target database. Author: Pavel Stehule with changes by me Ryan Lambert and Amit Kapila Discussion: https://postgr.es/m/CAP_rwwmLJJbn70vLOZFpxGw3XD7nLB_7+NKz46H5EOO2k5H7OQ@mail.gmail.com
On 6th of November 2019, Tomas Vondra committed patch:
Allow sampling of statements depending on duration This allows logging a sample of statements, without incurring excessive log traffic (which may impact performance). This can be useful when analyzing workloads with lots of short queries. The sampling is configured using two new GUC parameters: * log_min_duration_sample - minimum required statement duration * log_statement_sample_rate - sample rate (0.0 - 1.0) Only statements with duration exceeding log_min_duration_sample are considered for sampling. To enable sampling, both those GUCs have to be set correctly. The existing log_min_duration_statement GUC has a higher priority, i.e. statements with duration exceeding log_min_duration_statement will be always logged, irrespectedly of how the sampling is configured. This means only configurations log_min_duration_sample < log_min_duration_statement do actually sample the statements, instead of logging everything. Author: Adrien Nayrat Discussion: https://postgr.es/m/-a8f7-3be2-155a-@anayrat.info
Continue reading Waiting for PostgreSQL 13 – Allow sampling of statements depending on duration
Added two new functions, which basically work only for JSON / YAML / XML plans.
First – the view of source explain is now syntax highlighted. Just click source button on one of these to see:
Next additon is text tab, which shows the same explain but converted to text-format.
Hope you'll find it useful.
Just now pushed new version of Pg::Explain Perl library that is handling parsing for explain.depesz.com.
There have been many changes, but the short summary is:
Hopefully it will not break anything for you 🙂
And as a final note: explain.depesz.com has been used to add almost 740kplans (out of which 120k were deleted). Currently database contains over 311k public (visible in history), not deleted, plans.
On 3rd of October 2019, Amit Kapila committed patch:
pgbench: add --partitions and --partition-method options. These new options allow users to partition the pgbench_accounts table by specifying the number of partitions and partitioning method. The values allowed for partitioning method are range and hash. This feature allows users to measure the overhead of partitioning if any. Author: Fabien COELHO Alvaro Herrera Discussion: https://postgr.es/m/alpine.DEB.2.21..7008@lancre
Continue reading Waiting for PostgreSQL 13 – pgbench: add –partitions and –partition-method options.
Recently I've seen case like:
Why? How to avoid the problem?
Continue reading How to run short ALTER TABLE without long locking concurrent queries
On 16th of September 2019, Alexander Korotkov committed two patches:
First patch:
Support for SSSSS datetime format pattern SQL Standard 2016 defines SSSSS format pattern for seconds past midnight in jsonpath .datetime() method and CAST (... FORMAT ...) SQL clause. In our datetime parsing engine we currently support it with SSSS name. This commit adds SSSSS as an alias for SSSS. Alias is added in favor of upcoming jsonpath .datetime() method. But it's also supported in to_date()/ to_timestamp() as positive side effect. Discussion: https://postgr.es/m/CAPpHfdsZgYEra_PeCLGNoXOWYx6iU-S3wF8aX0ObQUcZU%2B4XTw%40mail.gmail.com Author: Nikita Glukhov, Alexander Korotkov
and second one:
Support for FF1-FF6 datetime format patterns SQL Standard 2016 defines FF1-FF9 format patters for fractions of seconds in jsonpath .datetime() method and CAST (... FORMAT ...) SQL clause. Parsing engine of upcoming .datetime() method will be shared with to_date()/ to_timestamp(). This patch implements FF1-FF6 format patterns for upcoming jsonpath .datetime() method. to_date()/to_timestamp() functions will also get support of this format patterns as positive side effect. FF7-FF9 are not supported due to lack of precision in our internal timestamp representation. Extracted from original patch by Nikita Glukhov, Teodor Sigaev, Oleg Bartunov. Heavily revised by me. Discussion: https://postgr.es/m/-b497-f39a-923d-%402ndQuadrant.com Discussion: https://postgr.es/m/CAPpHfdsZgYEra_PeCLGNoXOWYx6iU-S3wF8aX0ObQUcZU%2B4XTw%40mail.gmail.com Author: Nikita Glukhov, Teodor Sigaev, Oleg Bartunov, Alexander Korotkov
Continue reading Waiting for PostgreSQL 13 – Support for FF1-FF6 and SSSS datetime format patterns