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Commit3e98c0b

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Add pg_backend_memory_contexts system view.
This view displays the usages of all the memory contexts of the serverprocess attached to the current session. This information is useful toinvestigate the cause of backend-local memory bloat.This information can be also collected by callingMemoryContextStats(TopMemoryContext) via a debugger. But this techniquecannot be uesd in some environments because no debugger is available there.And it outputs lots of text messages and it's not easy to analyze them.So, pg_backend_memory_contexts view allows us to access to backend-localmemory contexts information more easily.Bump catalog version.Author: Atsushi Torikoshi, Fujii MasaoReviewed-by: Tatsuhito Kasahara, Andres Freund, Daniel Gustafsson, Robert Haas, Michael PaquierDiscussion:https://postgr.es/m/72a656e0f71d0860161e0b3f67e4d771@oss.nttdata.com
1 parent07f32fc commit3e98c0b

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6 files changed

+283
-1
lines changed

6 files changed

+283
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lines changed

‎doc/src/sgml/catalogs.sgml

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@@ -9226,6 +9226,11 @@ SCRAM-SHA-256$<replaceable>&lt;iteration count&gt;</replaceable>:<replaceable>&l
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<entry>available versions of extensions</entry>
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</row>
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<row>
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<entry><link linkend="view-pg-backend-memory-contexts"><structname>pg_backend_memory_contexts</structname></link></entry>
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<entry>backend memory contexts</entry>
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</row>
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<row>
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<entry><link linkend="view-pg-config"><structname>pg_config</structname></link></entry>
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<entry>compile-time configuration parameters</entry>
@@ -9577,6 +9582,123 @@ SCRAM-SHA-256$<replaceable>&lt;iteration count&gt;</replaceable>:<replaceable>&l
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</para>
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</sect1>
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<sect1 id="view-pg-backend-memory-contexts">
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<title><structname>pg_backend_memory_contexts</structname></title>
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<indexterm zone="view-pg-backend-memory-contexts">
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<primary>pg_backend_memory_contexts</primary>
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</indexterm>
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<para>
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The view <structname>pg_backend_memory_contexts</structname> displays all
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the memory contexts of the server process attached to the current session.
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</para>
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<para>
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<structname>pg_backend_memory_contexts</structname> contains one row
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for each memory context.
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</para>
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<table>
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<title><structname>pg_backend_memory_contexts</structname> Columns</title>
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<tgroup cols="1">
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<thead>
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<row>
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<entry role="catalog_table_entry"><para role="column_definition">
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Column Type
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</para>
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<para>
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Description
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</para></entry>
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</row>
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</thead>
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<tbody>
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<row>
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<entry role="catalog_table_entry"><para role="column_definition">
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<structfield>name</structfield> <type>text</type>
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</para>
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<para>
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Name of the memory context
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</para></entry>
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</row>
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<row>
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<entry role="catalog_table_entry"><para role="column_definition">
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<structfield>ident</structfield> <type>text</type>
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</para>
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<para>
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Identification information of the memory context. This field is truncated at 1024 bytes
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</para></entry>
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</row>
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<row>
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<entry role="catalog_table_entry"><para role="column_definition">
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<structfield>parent</structfield> <type>text</type>
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</para>
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<para>
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Name of the parent of this memory context
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</para></entry>
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</row>
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<row>
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<entry role="catalog_table_entry"><para role="column_definition">
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<structfield>level</structfield> <type>int4</type>
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</para>
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<para>
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Distance from TopMemoryContext in context tree
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</para></entry>
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</row>
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<row>
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<entry role="catalog_table_entry"><para role="column_definition">
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<structfield>total_bytes</structfield> <type>int8</type>
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</para>
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<para>
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Total bytes allocated for this memory context
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</para></entry>
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</row>
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<row>
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<entry role="catalog_table_entry"><para role="column_definition">
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<structfield>total_nblocks</structfield> <type>int8</type>
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</para>
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<para>
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Total number of blocks allocated for this memory context
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</para></entry>
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</row>
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<row>
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<entry role="catalog_table_entry"><para role="column_definition">
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<structfield>free_bytes</structfield> <type>int8</type>
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</para>
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<para>
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Free space in bytes
9676+
</para></entry>
9677+
</row>
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<row>
9680+
<entry role="catalog_table_entry"><para role="column_definition">
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<structfield>free_chunks</structfield> <type>int8</type>
9682+
</para>
9683+
<para>
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Total number of free chunks
9685+
</para></entry>
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</row>
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<row>
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<entry role="catalog_table_entry"><para role="column_definition">
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<structfield>used_bytes</structfield> <type>int8</type>
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</para>
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<para>
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Used space in bytes
9694+
</para></entry>
9695+
</row>
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</tbody>
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</tgroup>
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</table>
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</sect1>
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95809702
<sect1 id="view-pg-config">
95819703
<title><structname>pg_config</structname></title>
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‎src/backend/catalog/system_views.sql

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Original file line numberDiff line numberDiff line change
@@ -554,6 +554,9 @@ CREATE VIEW pg_shmem_allocations AS
554554
REVOKE ALLON pg_shmem_allocationsFROM PUBLIC;
555555
REVOKE EXECUTEON FUNCTION pg_get_shmem_allocations()FROM PUBLIC;
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557+
CREATEVIEWpg_backend_memory_contextsAS
558+
SELECT*FROM pg_get_backend_memory_contexts();
559+
557560
-- Statistics views
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CREATEVIEWpg_stat_all_tablesAS

‎src/backend/utils/mmgr/mcxt.c

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Original file line numberDiff line numberDiff line change
@@ -21,8 +21,10 @@
2121

2222
#include"postgres.h"
2323

24+
#include"funcapi.h"
2425
#include"mb/pg_wchar.h"
2526
#include"miscadmin.h"
27+
#include"utils/builtins.h"
2628
#include"utils/memdebug.h"
2729
#include"utils/memutils.h"
2830

@@ -67,6 +69,12 @@ static void MemoryContextStatsPrint(MemoryContext context, void *passthru,
6769
#defineAssertNotInCriticalSection(context) \
6870
Assert(CritSectionCount == 0 || (context)->allowInCritSection)
6971

72+
/* ----------
73+
* The max bytes for showing identifiers of MemoryContext.
74+
* ----------
75+
*/
76+
#defineMEMORY_CONTEXT_IDENT_DISPLAY_SIZE1024
77+
7078
/*****************************************************************************
7179
* EXPORTED ROUTINES *
7280
*****************************************************************************/
@@ -1220,3 +1228,133 @@ pchomp(const char *in)
12201228
n--;
12211229
returnpnstrdup(in,n);
12221230
}
1231+
1232+
/*
1233+
* PutMemoryContextsStatsTupleStore
1234+
*One recursion level for pg_get_backend_memory_contexts.
1235+
*/
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staticvoid
1237+
PutMemoryContextsStatsTupleStore(Tuplestorestate*tupstore,
1238+
TupleDesctupdesc,MemoryContextcontext,
1239+
constchar*parent,intlevel)
1240+
{
1241+
#definePG_GET_BACKEND_MEMORY_CONTEXTS_COLS9
1242+
1243+
Datumvalues[PG_GET_BACKEND_MEMORY_CONTEXTS_COLS];
1244+
boolnulls[PG_GET_BACKEND_MEMORY_CONTEXTS_COLS];
1245+
MemoryContextCountersstat;
1246+
MemoryContextchild;
1247+
constchar*name;
1248+
constchar*ident;
1249+
1250+
AssertArg(MemoryContextIsValid(context));
1251+
1252+
name=context->name;
1253+
ident=context->ident;
1254+
1255+
/*
1256+
* To be consistent with logging output, we label dynahash contexts
1257+
* with just the hash table name as with MemoryContextStatsPrint().
1258+
*/
1259+
if (ident&&strcmp(name,"dynahash")==0)
1260+
{
1261+
name=ident;
1262+
ident=NULL;
1263+
}
1264+
1265+
/* Examine the context itself */
1266+
memset(&stat,0,sizeof(stat));
1267+
(*context->methods->stats) (context,NULL, (void*)&level,&stat);
1268+
1269+
memset(values,0,sizeof(values));
1270+
memset(nulls,0,sizeof(nulls));
1271+
1272+
if (name)
1273+
values[0]=CStringGetTextDatum(name);
1274+
else
1275+
nulls[0]= true;
1276+
1277+
if (ident)
1278+
{
1279+
intidlen=strlen(ident);
1280+
charclipped_ident[MEMORY_CONTEXT_IDENT_DISPLAY_SIZE];
1281+
1282+
/*
1283+
* Some identifiers such as SQL query string can be very long,
1284+
* truncate oversize identifiers.
1285+
*/
1286+
if (idlen >=MEMORY_CONTEXT_IDENT_DISPLAY_SIZE)
1287+
idlen=pg_mbcliplen(ident,idlen,MEMORY_CONTEXT_IDENT_DISPLAY_SIZE-1);
1288+
1289+
memcpy(clipped_ident,ident,idlen);
1290+
clipped_ident[idlen]='\0';
1291+
values[1]=CStringGetTextDatum(clipped_ident);
1292+
}
1293+
else
1294+
nulls[1]= true;
1295+
1296+
if (parent)
1297+
values[2]=CStringGetTextDatum(parent);
1298+
else
1299+
nulls[2]= true;
1300+
1301+
values[3]=Int32GetDatum(level);
1302+
values[4]=Int64GetDatum(stat.totalspace);
1303+
values[5]=Int64GetDatum(stat.nblocks);
1304+
values[6]=Int64GetDatum(stat.freespace);
1305+
values[7]=Int64GetDatum(stat.freechunks);
1306+
values[8]=Int64GetDatum(stat.totalspace-stat.freespace);
1307+
tuplestore_putvalues(tupstore,tupdesc,values,nulls);
1308+
1309+
for (child=context->firstchild;child!=NULL;child=child->nextchild)
1310+
{
1311+
PutMemoryContextsStatsTupleStore(tupstore,tupdesc,
1312+
child,name,level+1);
1313+
}
1314+
}
1315+
1316+
/*
1317+
* pg_get_backend_memory_contexts
1318+
*SQL SRF showing backend memory context.
1319+
*/
1320+
Datum
1321+
pg_get_backend_memory_contexts(PG_FUNCTION_ARGS)
1322+
{
1323+
ReturnSetInfo*rsinfo= (ReturnSetInfo*)fcinfo->resultinfo;
1324+
TupleDesctupdesc;
1325+
Tuplestorestate*tupstore;
1326+
MemoryContextper_query_ctx;
1327+
MemoryContextoldcontext;
1328+
1329+
/* check to see if caller supports us returning a tuplestore */
1330+
if (rsinfo==NULL|| !IsA(rsinfo,ReturnSetInfo))
1331+
ereport(ERROR,
1332+
(errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
1333+
errmsg("set-valued function called in context that cannot accept a set")));
1334+
if (!(rsinfo->allowedModes&SFRM_Materialize))
1335+
ereport(ERROR,
1336+
(errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
1337+
errmsg("materialize mode required, but it is not allowed in this context")));
1338+
1339+
/* Build a tuple descriptor for our result type */
1340+
if (get_call_result_type(fcinfo,NULL,&tupdesc)!=TYPEFUNC_COMPOSITE)
1341+
elog(ERROR,"return type must be a row type");
1342+
1343+
per_query_ctx=rsinfo->econtext->ecxt_per_query_memory;
1344+
oldcontext=MemoryContextSwitchTo(per_query_ctx);
1345+
1346+
tupstore=tuplestore_begin_heap(true, false,work_mem);
1347+
rsinfo->returnMode=SFRM_Materialize;
1348+
rsinfo->setResult=tupstore;
1349+
rsinfo->setDesc=tupdesc;
1350+
1351+
MemoryContextSwitchTo(oldcontext);
1352+
1353+
PutMemoryContextsStatsTupleStore(tupstore,tupdesc,
1354+
TopMemoryContext,NULL,0);
1355+
1356+
/* clean up and return the tuplestore */
1357+
tuplestore_donestoring(tupstore);
1358+
1359+
return (Datum)0;
1360+
}

‎src/include/catalog/catversion.h

Lines changed: 1 addition & 1 deletion
Original file line numberDiff line numberDiff line change
@@ -53,6 +53,6 @@
5353
*/
5454

5555
/*yyyymmddN */
56-
#defineCATALOG_VERSION_NO202007251
56+
#defineCATALOG_VERSION_NO202008191
5757

5858
#endif

‎src/include/catalog/pg_proc.dat

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Original file line numberDiff line numberDiff line change
@@ -7807,6 +7807,15 @@
78077807
proargnames => '{name,off,size,allocated_size}',
78087808
prosrc => 'pg_get_shmem_allocations' },
78097809

7810+
# memory context of local backend
7811+
{ oid => '2282', descr => 'information about all memory contexts of local backend',
7812+
proname => 'pg_get_backend_memory_contexts', prorows => '100', proretset => 't',
7813+
provolatile => 'v', proparallel => 'r', prorettype => 'record', proargtypes => '',
7814+
proallargtypes => '{text,text,text,int4,int8,int8,int8,int8,int8}',
7815+
proargmodes => '{o,o,o,o,o,o,o,o,o}',
7816+
proargnames => '{name, ident, parent, level, total_bytes, total_nblocks, free_bytes, free_chunks, used_bytes}',
7817+
prosrc => 'pg_get_backend_memory_contexts' },
7818+
78107819
# non-persistent series generator
78117820
{ oid => '1066', descr => 'non-persistent series generator',
78127821
proname => 'generate_series', prorows => '1000',

‎src/test/regress/expected/rules.out

Lines changed: 10 additions & 0 deletions
Original file line numberDiff line numberDiff line change
@@ -1324,6 +1324,16 @@ pg_available_extensions| SELECT e.name,
13241324
e.comment
13251325
FROM (pg_available_extensions() e(name, default_version, comment)
13261326
LEFT JOIN pg_extension x ON ((e.name = x.extname)));
1327+
pg_backend_memory_contexts| SELECT pg_get_backend_memory_contexts.name,
1328+
pg_get_backend_memory_contexts.ident,
1329+
pg_get_backend_memory_contexts.parent,
1330+
pg_get_backend_memory_contexts.level,
1331+
pg_get_backend_memory_contexts.total_bytes,
1332+
pg_get_backend_memory_contexts.total_nblocks,
1333+
pg_get_backend_memory_contexts.free_bytes,
1334+
pg_get_backend_memory_contexts.free_chunks,
1335+
pg_get_backend_memory_contexts.used_bytes
1336+
FROM pg_get_backend_memory_contexts() pg_get_backend_memory_contexts(name, ident, parent, level, total_bytes, total_nblocks, free_bytes, free_chunks, used_bytes);
13271337
pg_config| SELECT pg_config.name,
13281338
pg_config.setting
13291339
FROM pg_config() pg_config(name, setting);

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