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[PATCH v45 5/7] Doc part of shared-memory based stats collector. 5+ messages / 4 participants [nested] [flat]
* [PATCH v45 5/7] Doc part of shared-memory based stats collector. @ 2020-03-19 06:11 Kyotaro Horiguchi <[email protected]> 0 siblings, 0 replies; 5+ messages in thread From: Kyotaro Horiguchi @ 2020-03-19 06:11 UTC (permalink / raw) --- doc/src/sgml/catalogs.sgml | 6 +- doc/src/sgml/config.sgml | 34 ++++---- doc/src/sgml/high-availability.sgml | 13 +-- doc/src/sgml/monitoring.sgml | 127 +++++++++++++--------------- doc/src/sgml/ref/pg_dump.sgml | 9 +- 5 files changed, 90 insertions(+), 99 deletions(-) diff --git a/doc/src/sgml/catalogs.sgml b/doc/src/sgml/catalogs.sgml index 3a2266526c..4d8b92df72 100644 --- a/doc/src/sgml/catalogs.sgml +++ b/doc/src/sgml/catalogs.sgml @@ -9234,9 +9234,9 @@ SCRAM-SHA-256$<replaceable><iteration count></replaceable>:<replaceable>&l <para> <xref linkend="view-table"/> lists the system views described here. More detailed documentation of each view follows below. - There are some additional views that provide access to the results of - the statistics collector; they are described in <xref - linkend="monitoring-stats-views-table"/>. + There are some additional views that provide access to the activity + statistics; they are described in + <xref linkend="monitoring-stats-views-table"/>. </para> <para> diff --git a/doc/src/sgml/config.sgml b/doc/src/sgml/config.sgml index 7c0a673a8d..f6c80df988 100644 --- a/doc/src/sgml/config.sgml +++ b/doc/src/sgml/config.sgml @@ -7327,11 +7327,11 @@ COPY postgres_log FROM '/full/path/to/logfile.csv' WITH csv; <title>Run-time Statistics</title> <sect2 id="runtime-config-statistics-collector"> - <title>Query and Index Statistics Collector</title> + <title>Query and Index Activity Statistics</title> <para> - These parameters control server-wide statistics collection features. - When statistics collection is enabled, the data that is produced can be + These parameters control server-wide activity statistics features. + When activity statistics is enabled, the data that is produced can be accessed via the <structname>pg_stat</structname> and <structname>pg_statio</structname> family of system views. Refer to <xref linkend="monitoring"/> for more information. @@ -7347,14 +7347,13 @@ COPY postgres_log FROM '/full/path/to/logfile.csv' WITH csv; </term> <listitem> <para> - Enables the collection of information on the currently - executing command of each session, along with the time when - that command began execution. This parameter is on by - default. Note that even when enabled, this information is not - visible to all users, only to superusers and the user owning - the session being reported on, so it should not represent a - security risk. - Only superusers can change this setting. + Enables activity tracking on the currently executing command of + each session, along with the time when that command began + execution. This parameter is on by default. Note that even when + enabled, this information is not visible to all users, only to + superusers and the user owning the session being reported on, so it + should not represent a security risk. Only superusers can change this + setting. </para> </listitem> </varlistentry> @@ -7385,9 +7384,9 @@ COPY postgres_log FROM '/full/path/to/logfile.csv' WITH csv; </term> <listitem> <para> - Enables collection of statistics on database activity. + Enables tracking of database activity. This parameter is on by default, because the autovacuum - daemon needs the collected information. + daemon needs the activity information. Only superusers can change this setting. </para> </listitem> @@ -8485,7 +8484,7 @@ COPY postgres_log FROM '/full/path/to/logfile.csv' WITH csv; <listitem> <para> Specifies the fraction of the total number of heap tuples counted in - the previous statistics collection that can be inserted without + the previously collected statistics that can be inserted without incurring an index scan at the <command>VACUUM</command> cleanup stage. This setting currently applies to B-tree indexes only. </para> @@ -8497,9 +8496,10 @@ COPY postgres_log FROM '/full/path/to/logfile.csv' WITH csv; the index contains deleted pages that can be recycled during cleanup. Index statistics are considered to be stale if the number of newly inserted tuples exceeds the <varname>vacuum_cleanup_index_scale_factor</varname> - fraction of the total number of heap tuples detected by the previous - statistics collection. The total number of heap tuples is stored in - the index meta-page. Note that the meta-page does not include this data + + fraction of the total number of heap tuples in the previously + collected statistics. The total number of heap tuples is stored in the + index meta-page. Note that the meta-page does not include this data until <command>VACUUM</command> finds no dead tuples, so B-tree index scan at the cleanup stage can only be skipped if the second and subsequent <command>VACUUM</command> cycles detect no dead tuples. diff --git a/doc/src/sgml/high-availability.sgml b/doc/src/sgml/high-availability.sgml index efc382cb8d..6c620469eb 100644 --- a/doc/src/sgml/high-availability.sgml +++ b/doc/src/sgml/high-availability.sgml @@ -2338,12 +2338,13 @@ LOG: database system is ready to accept read only connections </para> <para> - The statistics collector is active during recovery. All scans, reads, blocks, - index usage, etc., will be recorded normally on the standby. Replayed - actions will not duplicate their effects on primary, so replaying an - insert will not increment the Inserts column of pg_stat_user_tables. - The stats file is deleted at the start of recovery, so stats from primary - and standby will differ; this is considered a feature, not a bug. + The activity statistics is collected during recovery. All scans, reads, + blocks, index usage, etc., will be recorded normally on the + standby. Replayed actions will not duplicate their effects on primary, so + replaying an insert will not increment the Inserts column of + pg_stat_user_tables. The activity statistics is reset at the start of + recovery, so stats from primary and standby will differ; this is + considered a feature, not a bug. </para> <para> diff --git a/doc/src/sgml/monitoring.sgml b/doc/src/sgml/monitoring.sgml index 3cdb1aff3c..afa8c35127 100644 --- a/doc/src/sgml/monitoring.sgml +++ b/doc/src/sgml/monitoring.sgml @@ -22,7 +22,7 @@ <para> Several tools are available for monitoring database activity and analyzing performance. Most of this chapter is devoted to describing - <productname>PostgreSQL</productname>'s statistics collector, + <productname>PostgreSQL</productname>'s activity statistics, but one should not neglect regular Unix monitoring programs such as <command>ps</command>, <command>top</command>, <command>iostat</command>, and <command>vmstat</command>. Also, once one has identified a @@ -53,7 +53,6 @@ postgres 15554 0.0 0.0 57536 1184 ? Ss 18:02 0:00 postgres: back postgres 15555 0.0 0.0 57536 916 ? Ss 18:02 0:00 postgres: checkpointer postgres 15556 0.0 0.0 57536 916 ? Ss 18:02 0:00 postgres: walwriter postgres 15557 0.0 0.0 58504 2244 ? Ss 18:02 0:00 postgres: autovacuum launcher -postgres 15558 0.0 0.0 17512 1068 ? Ss 18:02 0:00 postgres: stats collector postgres 15582 0.0 0.0 58772 3080 ? Ss 18:04 0:00 postgres: joe runbug 127.0.0.1 idle postgres 15606 0.0 0.0 58772 3052 ? Ss 18:07 0:00 postgres: tgl regression [local] SELECT waiting postgres 15610 0.0 0.0 58772 3056 ? Ss 18:07 0:00 postgres: tgl regression [local] idle in transaction @@ -65,9 +64,8 @@ postgres 15610 0.0 0.0 58772 3056 ? Ss 18:07 0:00 postgres: tgl primary server process. The command arguments shown for it are the same ones used when it was launched. The next five processes are background worker processes automatically launched by the - primary process. (The <quote>stats collector</quote> process will not be present - if you have set the system not to start the statistics collector; likewise - the <quote>autovacuum launcher</quote> process can be disabled.) + primary process. (The <quote>autovacuum launcher</quote> process will not + be present if you have set the system not to start it.) Each of the remaining processes is a server process handling one client connection. Each such process sets its command line display in the form @@ -130,20 +128,21 @@ postgres 27093 0.0 0.0 30096 2752 ? Ss 11:34 0:00 postgres: ser </sect1> <sect1 id="monitoring-stats"> - <title>The Statistics Collector</title> + <title>The Activity Statistics</title> <indexterm zone="monitoring-stats"> <primary>statistics</primary> </indexterm> <para> - <productname>PostgreSQL</productname>'s <firstterm>statistics collector</firstterm> - is a subsystem that supports collection and reporting of information about - server activity. Presently, the collector can count accesses to tables - and indexes in both disk-block and individual-row terms. It also tracks - the total number of rows in each table, and information about vacuum and - analyze actions for each table. It can also count calls to user-defined - functions and the total time spent in each one. + <productname>PostgreSQL</productname>'s <firstterm>activity + statistics</firstterm> is a subsystem that supports tracking and reporting + of information about server activity. Presently, the activity statistics + tracks the count of accesses to tables and indexes in both disk-block and + individual-row terms. It also tracks the total number of rows in each + table, and information about vacuum and analyze actions for each table. It + can also track calls to user-defined functions and the total time spent in + each one. </para> <para> @@ -151,15 +150,15 @@ postgres 27093 0.0 0.0 30096 2752 ? Ss 11:34 0:00 postgres: ser information about exactly what is going on in the system right now, such as the exact command currently being executed by other server processes, and which other connections exist in the system. This facility is independent - of the collector process. + of the activity statistics. </para> <sect2 id="monitoring-stats-setup"> - <title>Statistics Collection Configuration</title> + <title>Activity Statistics Configuration</title> <para> - Since collection of statistics adds some overhead to query execution, - the system can be configured to collect or not collect information. + Since tracking for the activity statistics adds some overhead to query + execution, the system can be configured to track or not track activity. This is controlled by configuration parameters that are normally set in <filename>postgresql.conf</filename>. (See <xref linkend="runtime-config"/> for details about setting configuration parameters.) @@ -172,7 +171,7 @@ postgres 27093 0.0 0.0 30096 2752 ? Ss 11:34 0:00 postgres: ser <para> The parameter <xref linkend="guc-track-counts"/> controls whether - statistics are collected about table and index accesses. + to track activity about table and index accesses. </para> <para> @@ -196,18 +195,11 @@ postgres 27093 0.0 0.0 30096 2752 ? Ss 11:34 0:00 postgres: ser </para> <para> - The statistics collector transmits the collected information to other - <productname>PostgreSQL</productname> processes through temporary files. - These files are stored in the directory named by the - <xref linkend="guc-stats-temp-directory"/> parameter, - <filename>pg_stat_tmp</filename> by default. - For better performance, <varname>stats_temp_directory</varname> can be - pointed at a RAM-based file system, decreasing physical I/O requirements. - When the server shuts down cleanly, a permanent copy of the statistics - data is stored in the <filename>pg_stat</filename> subdirectory, so that - statistics can be retained across server restarts. When recovery is - performed at server start (e.g., after immediate shutdown, server crash, - and point-in-time recovery), all statistics counters are reset. + down cleanly, a permanent copy of the statistics data is stored in + the <filename>pg_stat</filename> subdirectory, so that statistics can be + retained across server restarts. When recovery is performed at server + start (e.g. after immediate shutdown, server crash, and point-in-time + recovery), all statistics counters are reset. </para> </sect2> @@ -220,48 +212,46 @@ postgres 27093 0.0 0.0 30096 2752 ? Ss 11:34 0:00 postgres: ser linkend="monitoring-stats-dynamic-views-table"/>, are available to show the current state of the system. There are also several other views, listed in <xref - linkend="monitoring-stats-views-table"/>, available to show the results - of statistics collection. Alternatively, one can - build custom views using the underlying statistics functions, as discussed - in <xref linkend="monitoring-stats-functions"/>. + linkend="monitoring-stats-views-table"/>, available to show the activity + statistics. Alternatively, one can build custom views using the underlying + statistics functions, as discussed in + <xref linkend="monitoring-stats-functions"/>. </para> <para> - When using the statistics to monitor collected data, it is important - to realize that the information does not update instantaneously. - Each individual server process transmits new statistical counts to - the collector just before going idle; so a query or transaction still in - progress does not affect the displayed totals. Also, the collector itself - emits a new report at most once per <varname>PGSTAT_STAT_INTERVAL</varname> - milliseconds (500 ms unless altered while building the server). So the - displayed information lags behind actual activity. However, current-query - information collected by <varname>track_activities</varname> is - always up-to-date. + When using the activity statistics, it is important to realize that the + information does not update instantaneously. Each individual server writes + out new statistical counts just before going idle, not frequent than once + per <varname>PGSTAT_STAT_INTERVAL</varname> milliseconds (1 second unless + altered while building the server); so a query or transaction still in + progress does not affect the displayed totals. However, current-query + information tracked by <varname>track_activities</varname> is always + up-to-date. </para> <para> Another important point is that when a server process is asked to display - any of these statistics, it first fetches the most recent report emitted by - the collector process and then continues to use this snapshot for all - statistical views and functions until the end of its current transaction. - So the statistics will show static information as long as you continue the - current transaction. Similarly, information about the current queries of - all sessions is collected when any such information is first requested - within a transaction, and the same information will be displayed throughout - the transaction. - This is a feature, not a bug, because it allows you to perform several - queries on the statistics and correlate the results without worrying that - the numbers are changing underneath you. But if you want to see new - results with each query, be sure to do the queries outside any transaction - block. Alternatively, you can invoke + any of these statistics, it first reads the current statistics and then + continues to use this snapshot for all statistical views and functions + until the end of its current transaction. So the statistics will show + static information as long as you continue the current transaction. + Similarly, information about the current queries of all sessions is tracked + when any such information is first requested within a transaction, and the + same information will be displayed throughout the transaction. This is a + feature, not a bug, because it allows you to perform several queries on the + statistics and correlate the results without worrying that the numbers are + changing underneath you. But if you want to see new results with each + query, be sure to do the queries outside any transaction block. + Alternatively, you can invoke <function>pg_stat_clear_snapshot</function>(), which will discard the current transaction's statistics snapshot (if any). The next use of statistical information will cause a new snapshot to be fetched. </para> - + <para> - A transaction can also see its own statistics (as yet untransmitted to the - collector) in the views <structname>pg_stat_xact_all_tables</structname>, + A transaction can also see its own statistics (as yet unwritten to the + server-wide activity statistics) in the + views <structname>pg_stat_xact_all_tables</structname>, <structname>pg_stat_xact_sys_tables</structname>, <structname>pg_stat_xact_user_tables</structname>, and <structname>pg_stat_xact_user_functions</structname>. These numbers do not act as @@ -643,7 +633,7 @@ postgres 27093 0.0 0.0 30096 2752 ? Ss 11:34 0:00 postgres: ser kernel's I/O cache, and might therefore still be fetched without requiring a physical read. Users interested in obtaining more detailed information on <productname>PostgreSQL</productname> I/O behavior are - advised to use the <productname>PostgreSQL</productname> statistics collector + advised to use the <productname>PostgreSQL</productname> activity statistics in combination with operating system utilities that allow insight into the kernel's handling of I/O. </para> @@ -1080,10 +1070,6 @@ postgres 27093 0.0 0.0 30096 2752 ? Ss 11:34 0:00 postgres: ser <entry><literal>LogicalLauncherMain</literal></entry> <entry>Waiting in main loop of logical replication launcher process.</entry> </row> - <row> - <entry><literal>PgStatMain</literal></entry> - <entry>Waiting in main loop of statistics collector process.</entry> - </row> <row> <entry><literal>RecoveryWalStream</literal></entry> <entry>Waiting in main loop of startup process for WAL to arrive, during @@ -1838,6 +1824,10 @@ postgres 27093 0.0 0.0 30096 2752 ? Ss 11:34 0:00 postgres: ser </thead> <tbody> + <row> + <entry><literal>ActivityStatistics</literal></entry> + <entry>Waiting to write out activity statistics to shared memory.</entry> + </row> <row> <entry><literal>AddinShmemInit</literal></entry> <entry>Waiting to manage an extension's space allocation in shared @@ -5996,9 +5986,10 @@ SELECT pg_stat_get_backend_pid(s.backendid) AS pid, <entry><literal>performing final cleanup</literal></entry> <entry> <command>VACUUM</command> is performing final cleanup. During this phase, - <command>VACUUM</command> will vacuum the free space map, update statistics - in <literal>pg_class</literal>, and report statistics to the statistics - collector. When this phase is completed, <command>VACUUM</command> will end. + <command>VACUUM</command> will vacuum the free space map, update + statistics in <literal>pg_class</literal>, and system-wide activity + statistics. When this phase is completed, <command>VACUUM</command> + will end. </entry> </row> </tbody> diff --git a/doc/src/sgml/ref/pg_dump.sgml b/doc/src/sgml/ref/pg_dump.sgml index dcb25dc3cd..7507783eaa 100644 --- a/doc/src/sgml/ref/pg_dump.sgml +++ b/doc/src/sgml/ref/pg_dump.sgml @@ -1280,11 +1280,10 @@ PostgreSQL documentation </para> <para> - The database activity of <application>pg_dump</application> is - normally collected by the statistics collector. If this is - undesirable, you can set parameter <varname>track_counts</varname> - to false via <envar>PGOPTIONS</envar> or the <literal>ALTER - USER</literal> command. + The database activity of <application>pg_dump</application> is normally + collected. If this is undesirable, you can set + parameter <varname>track_counts</varname> to false + via <envar>PGOPTIONS</envar> or the <literal>ALTER USER</literal> command. </para> </refsect1> -- 2.27.0 ----Next_Part(Fri_Jan__8_10_24_34_2021_185)-- Content-Type: Text/X-Patch; charset=us-ascii Content-Transfer-Encoding: 7bit Content-Disposition: inline; filename="v45-0006-Remove-the-GUC-stats_temp_directory.patch" ^ permalink raw reply [nested|flat] 5+ messages in thread
* Re: [DOC] Add detail regarding resource consumption wrt max_connections @ 2024-01-12 22:14 Cary Huang <[email protected]> 0 siblings, 1 reply; 5+ messages in thread From: Cary Huang @ 2024-01-12 22:14 UTC (permalink / raw) To: [email protected]; +Cc: Roberto Mello <[email protected]> The following review has been posted through the commitfest application: make installcheck-world: tested, passed Implements feature: tested, passed Spec compliant: tested, passed Documentation: tested, passed I think it is good to warn the user about the increased allocation of memory for certain parameters so that they do not abuse it by setting it to a huge number without knowing the consequences. It is true that max_connections can increase the size of proc array and other resources, which are allocated in the shared buffer, which also means less shared buffer to perform regular data operations. I am sure this is not the only parameter that affects the memory allocation. "max_prepared_xacts" can also affect the shared memory allocation too so the same warning message applies here as well. Maybe there are other parameters with similar effects. Instead of stating that higher max_connections results in higher allocation, It may be better to tell the user that if the value needs to be set much higher, consider increasing the "shared_buffers" setting as well. thank you ----------------------- Cary Huang Highgo Software Canada www.highgo.ca ^ permalink raw reply [nested|flat] 5+ messages in thread
* Re: [DOC] Add detail regarding resource consumption wrt max_connections @ 2024-01-13 17:31 Roberto Mello <[email protected]> parent: Cary Huang <[email protected]> 0 siblings, 1 reply; 5+ messages in thread From: Roberto Mello @ 2024-01-13 17:31 UTC (permalink / raw) To: Cary Huang <[email protected]>; +Cc: [email protected] On Fri, Jan 12, 2024 at 3:15 PM Cary Huang <[email protected]> wrote: > I think it is good to warn the user about the increased allocation of > memory for certain parameters so that they do not abuse it by setting it to > a huge number without knowing the consequences. > > It is true that max_connections can increase the size of proc array and > other resources, which are allocated in the shared buffer, which also means > less shared buffer to perform regular data operations. I am sure this is > not the only parameter that affects the memory allocation. > "max_prepared_xacts" can also affect the shared memory allocation too so > the same warning message applies here as well. Maybe there are other > parameters with similar effects. > > Instead of stating that higher max_connections results in higher > allocation, It may be better to tell the user that if the value needs to be > set much higher, consider increasing the "shared_buffers" setting as well. > Appreciate the review, Cary. My goal was to inform the reader that there are implications to setting max_connections higher. I've personally seen a user mindlessly set this to 50k connections, unaware it would cause unintended consequences. I can add a suggestion for the user to consider increasing shared_buffers in accordance with higher max_connections, but it would be better if there was a "rule of thumb" guideline to go along. I'm open to suggestions. I can revise with a similar warning in max_prepared_xacts as well. Sincerely, Roberto ^ permalink raw reply [nested|flat] 5+ messages in thread
* Re: [DOC] Add detail regarding resource consumption wrt max_connections @ 2024-01-19 22:37 [email protected] parent: Roberto Mello <[email protected]> 0 siblings, 1 reply; 5+ messages in thread From: [email protected] @ 2024-01-19 22:37 UTC (permalink / raw) To: Roberto Mello <[email protected]>; Cary Huang <[email protected]>; +Cc: [email protected] On Sat, 2024-01-13 at 10:31 -0700, Roberto Mello wrote: > On Fri, Jan 12, 2024 at 3:15 PM Cary Huang <[email protected]> > wrote: > > I think it is good to warn the user about the increased allocation > > of memory for certain parameters so that they do not abuse it by > > setting it to a huge number without knowing the consequences. > > > > It is true that max_connections can increase the size of proc array > > and other resources, which are allocated in the shared buffer, > > which also means less shared buffer to perform regular data > > operations. I am sure this is not the only parameter that affects > > the memory allocation. "max_prepared_xacts" can also affect the > > shared memory allocation too so the same warning message applies > > here as well. Maybe there are other parameters with similar > > effects. > > > > Instead of stating that higher max_connections results in higher > > allocation, It may be better to tell the user that if the value > > needs to be set much higher, consider increasing the > > "shared_buffers" setting as well. > > > > > Appreciate the review, Cary. > > My goal was to inform the reader that there are implications to > setting max_connections higher. I've personally seen a user > mindlessly set this to 50k connections, unaware it would cause > unintended consequences. > > I can add a suggestion for the user to consider increasing > shared_buffers in accordance with higher max_connections, but it > would be better if there was a "rule of thumb" guideline to go along. > I'm open to suggestions. > > I can revise with a similar warning in max_prepared_xacts as well. > > Sincerely, > > Roberto Can a "close enough" rule of thumb be calculated from: postgresql.conf -> log_min_messages = debug3 start postgresql with varying max_connections to get CreateSharedMemoryAndSemaphores() sizes to generate a rough equation postgresql-12-main.log max_connections=100 75:2024-01-19 17:04:56.544 EST [2762535] DEBUG: invoking IpcMemoryCreate(size=149110784) 0.149110784GB max_connections=10000 1203:2024-01-19 17:06:13.502 EST [2764895] DEBUG: invoking IpcMemoryCreate(size=644997120) 0.64499712GB max_connections=20000 5248:2024-01-19 17:24:27.956 EST [2954550] DEBUG: invoking IpcMemoryCreate(size=1145774080) 1.14577408GB max_connections=50000 2331:2024-01-19 17:07:27.716 EST [2767079] DEBUG: invoking IpcMemoryCreate(size=2591490048) 2.591490048GB from lines 184-186 $ rg -B28 -A35 'invoking IpcMemoryCreate' backend/storage/ipc/ipci.c 158-/* 159- * CreateSharedMemoryAndSemaphores 160- * Creates and initializes shared memory and semaphores. 161- * 162- * This is called by the postmaster or by a standalone backend. 163- * It is also called by a backend forked from the postmaster in the 164- * EXEC_BACKEND case. In the latter case, the shared memory segment 165- * already exists and has been physically attached to, but we have to 166- * initialize pointers in local memory that reference the shared structures, 167- * because we didn't inherit the correct pointer values from the postmaster 168- * as we do in the fork() scenario. The easiest way to do that is to run 169- * through the same code as before. (Note that the called routines mostly 170- * check IsUnderPostmaster, rather than EXEC_BACKEND, to detect this case. 171- * This is a bit code-wasteful and could be cleaned up.) 172- */ 173-void 174-CreateSharedMemoryAndSemaphores(void) 175-{ 176- PGShmemHeader *shim = NULL; 177- 178- if (!IsUnderPostmaster) 179- { 180- PGShmemHeader *seghdr; 181- Size size; 182- int numSemas; 183- 184- /* Compute the size of the shared-memory block */ 185- size = CalculateShmemSize(&numSemas); 186: elog(DEBUG3, "invoking IpcMemoryCreate(size=%zu)", size); 187- 188- /* 189- * Create the shmem segment 190- */ 191- seghdr = PGSharedMemoryCreate(size, &shim); 192- 193- InitShmemAccess(seghdr); 194- 195- /* 196- * Create semaphores 197- */ 198- PGReserveSemaphores(numSemas); 199- 200- /* 201- * If spinlocks are disabled, initialize emulation layer (which 202- * depends on semaphores, so the order is important here). 203- */ 204-#ifndef HAVE_SPINLOCKS 205- SpinlockSemaInit(); 206-#endif 207- } 208- else 209- { 210- /* 211- * We are reattaching to an existing shared memory segment. This 212- * should only be reached in the EXEC_BACKEND case. 213- */ 214-#ifndef EXEC_BACKEND 215- elog(PANIC, "should be attached to shared memory already"); 216-#endif 217- } 218- 219- /* 220- * Set up shared memory allocation mechanism 221- */ ^ permalink raw reply [nested|flat] 5+ messages in thread
* Re: [DOC] Add detail regarding resource consumption wrt max_connections @ 2024-01-22 13:58 [email protected] parent: [email protected] 0 siblings, 0 replies; 5+ messages in thread From: [email protected] @ 2024-01-22 13:58 UTC (permalink / raw) To: Roberto Mello <[email protected]>; Cary Huang <[email protected]>; +Cc: [email protected] On Fri, 2024-01-19 at 17:37 -0500, [email protected] wrote: > On Sat, 2024-01-13 at 10:31 -0700, Roberto Mello wrote: > > > > I can add a suggestion for the user to consider increasing > > shared_buffers in accordance with higher max_connections, but it > > would be better if there was a "rule of thumb" guideline to go > > along. I'm open to suggestions. > > > > I can revise with a similar warning in max_prepared_xacts as well. > > > > Sincerely, > > > > Roberto > > Can a "close enough" rule of thumb be calculated from: > postgresql.conf -> log_min_messages = debug3 > > start postgresql with varying max_connections to get > CreateSharedMemoryAndSemaphores() sizes to generate a rough equation > or maybe it would be sufficient to advise to set log_min_messages = debug3 on a test DB and start/stop it with varying values of max_connections and look at the differing values in DEBUG: invoking IpcMemoryCreate(size=...) log messages for themselves. ^ permalink raw reply [nested|flat] 5+ messages in thread
end of thread, other threads:[~2024-01-22 13:58 UTC | newest] Thread overview: 5+ messages (download: mbox mbox.gz follow: Atom feed) -- links below jump to the message on this page -- 2020-03-19 06:11 [PATCH v45 5/7] Doc part of shared-memory based stats collector. Kyotaro Horiguchi <[email protected]> 2024-01-12 22:14 Re: [DOC] Add detail regarding resource consumption wrt max_connections Cary Huang <[email protected]> 2024-01-13 17:31 ` Re: [DOC] Add detail regarding resource consumption wrt max_connections Roberto Mello <[email protected]> 2024-01-19 22:37 ` Re: [DOC] Add detail regarding resource consumption wrt max_connections [email protected] 2024-01-22 13:58 ` Re: [DOC] Add detail regarding resource consumption wrt max_connections [email protected]
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