* PG-607: Allow histogram to track queries in sub-ms time brackets
Updated the GUC configuration and the relevant histogram functionality
to track queries in lower cardinality than ms. This is done by saving
the GUC values for histogram min and max values in real (double) type.
All test cases except for the 030 tap test are passing. The test case
needs an update.
* Fixing regression issues for v12 and below because of histogram changes.
* PG-606: New GUC required for enabling/disabling of pgsm_query_id calculation
Adds a new GUC pg_stat_monitor.pgsm_enable_pgsm_query_id to enable/disable
pgsm query id calculation. Apart from that patch also refactors the GUC-related
code to match PostgreSQL conventions.
Moreover, the commit also changes the pgsm_enable_overflow GUC to boolean
instead of enum.
Saving the client IP address once per the lifetime of a backend. This avoid
the expensive operation multiple times, and hence improving performance
significantly.
Performance related changes where some calculations are moved out
of the spinlock in the pgsm_update_entry function. This should
improve the performance a bit.
Also, moved the histogram calculation function to init. The update
function now only searches an array rather than recalculatiing the
histogram bucket timings.
Updated conditional statement to update parent query only when
required.
Saving the client IP address once per the lifetime of a backend. This avoid
the expensive operation multiple times, and hence improving performance
significantly.
This bug uncovered serious issues with how the data was being stored by PSGM.
So it require a complete redesign.
pg_stat_monitor now stores the data locally within the backend process's local
memory. The data is only stored when the query completes. This reduces the
number of lock acquisitions that were previously needed during various stages
of the execution. Also, this avoids data loss in case the current bucket
changes during execution. Also, the unavailability of jumble state during later
stages of executions was causing pg_stat_monitor to save non-normalized query.
This was a major problem as well.
pg_stat_monitor specific memory context is implemented. It is used for saving
data locally. The context memory callback helps us clear the locally saved data
so that we do not store it multiple times in the shared hash.
As part of this major rewrite, pgss reference in function and variable names
is changed to pgsm. Memory footprint for the entries is reduced, data types
are corrected where needed, and we've removed unused variables, functions and
macros.
This patch was mutually created by:
Co-authored-by: Hamid Akhtar <hamid.akhtar@percona.com>
Co-authored-by: Muhammad Usama <muhammad.usama@percona.com>
Removed use of String::Util perl module from TAP test cases, and now using
Text::Trim module instead, as that is more stable. Also removed the
Data::Str2Num perl module as it was not needed any more.
Disallow V1 API to be used with V2.0 lib and remove pg_stat_monitor--1.0.sql
as part of that. A few adjustments to 1.x to 2.0 upgrade script are also
part of the commit
Resolved the issue with histogram outlier buckets. Also updated
the printing of bucket ranges to be in correct set notation with
reference to brackets. The lower bounds of buckets always have an
exclusive range except for the first bucket, and the upper bounds
always have an inclusive value.
( or ) => exclusive
{ or } => inclusive
The entire range is enclosed within the {} brackets.
for utility statements as well
Added the necessary capture of resource usage in the process
utility function. We are now storing CPU and user timings for a
utility statement.
As an observability tool that serves data to other tools, data must be output without any loss. So rounding off causes data loss and rounding off errors when comparing different columns.
Therefore, it was decided to eliminate rounding off when outputting values. Any consumer of this data should round off data to whatever precision it prefers.
This behaviour is also consistent with pg_stat_statements.
1) Added the Group by clause to make sure that bucket change doesn't have any
impact on aggregates of queries.
2) Updated column names where required.
3) Updated pgbench parameters to reduce the time taken by test case, around
70-80% decrease in time taken by test case.
1) Added the Group by clause to make sure that bucket change doesn't have any
impact on aggregates of queries.
2) Updated column names where required.
3) Updated pgbench parameters to reduce the time taken by test case, around
70-80% decrease in time taken by test case.
There is no specific test case where I can either reproduce or validate
the fix. Though, one of the suspects is this condition in pgss_store.
Therefore removed, and it requires verification.
Replaced the error on server start with a warning. The functionality
now handles "pgsm_histogram_buckets" as the maximum number of histogram
buckets to be created. On init, pg_stat_monitor calculates the max
number of buckets that can be created within the given min/max time
range. If the number is below the user configuration, it emits a
warning in the log file stating the number of max buckets set.
Added buckets for queries that take less than minimum histogram time
and one for the ones taking more than the max value specified.
Also, in case the buckets end up overlapping, on server start, an
error will be thrown informing the user of this issue and requesting
a rectification.
Refactored the code to consolidate the calculations in a single
function.
* PG-543: pg_stat_monitor: PostgreSQL's pg_stat_statements compatible view.
The view now carries all the columns as pg_stat_statements. This required fixing
data types of some of the columns, renaming a few, as well inclusion of new
columns to make the view fully compatible with pg_stat_statements.
* PG-543: pg_stat_monitor: PostgreSQL's pg_stat_statements compatible view.
Updating the upgrade sql file from 1.0 to 2.0 version linked with this issue
changes.
* PG-543: pg_stat_monitor: PostgreSQL's pg_stat_statements compatible view.
Updating datum calls to use UInt64 rather than Int64.
Hamid Akhtar
EvgeniyPatlan
Naeem Akhter
Muhammad Usama
Ibrar Ahmed
Vadim Yalovets
Muhammad Usama
Kai Wagner
Naeem Akhter