Hi,
Attached a rebased version of the patch.
--
Regards,
--
Atsushi Torikoshi
Seconded from NTT DATA GROUP CORPORATION to SRA OSS K.K.
From 112467238f585bb3398d86ac6e1a71caa6549fb4 Mon Sep 17 00:00:00 2001
From: Atsushi Torikoshi <torikos...@oss.nttdata.com>
Date: Thu, 24 Apr 2025 20:50:41 +0900
Subject: [PATCH v44] Add function to log the plan of the currently running
query
Currently, we have to wait for the query execution to finish
to know its plan either using EXPLAIN ANALYZE or auto_explain.
This is not so convenient, for example when investigating
long-running queries on production environments.
To improve this situation, this patch adds pg_log_query_plan()
function that requests to log the plan of the currently
executing query.
On receipt of the request, codes for logging plan is wrapped
to every ExecProcNode and when the executor runs one of
ExecProcNode, the plan is actually logged. These wrappers are
unwrapped when once the plan is logged.
In this way, we can avoid adding the overhead which we'll face
when adding CHECK_FOR_INTERRUPTS() like mechanisms in somewhere
in executor codes safely.
By default, only superusers are allowed to request to log the
plans because allowing any users to issue this request at an
unbounded rate would cause lots of log messages and which can
lead to denial of service.
---
contrib/auto_explain/auto_explain.c | 24 +-
doc/src/sgml/func.sgml | 55 +++
src/backend/access/transam/xact.c | 7 +
src/backend/catalog/system_functions.sql | 2 +
src/backend/commands/Makefile | 1 +
src/backend/commands/dynamic_explain.c | 368 +++++++++++++++++++
src/backend/commands/explain.c | 38 +-
src/backend/commands/meson.build | 1 +
src/backend/executor/execMain.c | 10 +
src/backend/storage/ipc/procsignal.c | 4 +
src/backend/tcop/postgres.c | 4 +
src/backend/utils/init/globals.c | 2 +
src/include/catalog/pg_proc.dat | 6 +
src/include/commands/dynamic_explain.h | 26 ++
src/include/commands/explain.h | 5 +
src/include/commands/explain_state.h | 1 +
src/include/miscadmin.h | 1 +
src/include/nodes/execnodes.h | 3 +
src/include/storage/procsignal.h | 2 +
src/include/tcop/pquery.h | 1 -
src/test/regress/expected/misc_functions.out | 54 ++-
src/test/regress/sql/misc_functions.sql | 41 ++-
22 files changed, 613 insertions(+), 43 deletions(-)
create mode 100644 src/backend/commands/dynamic_explain.c
create mode 100644 src/include/commands/dynamic_explain.h
diff --git a/contrib/auto_explain/auto_explain.c b/contrib/auto_explain/auto_explain.c
index cd6625020a..e720ddf39f 100644
--- a/contrib/auto_explain/auto_explain.c
+++ b/contrib/auto_explain/auto_explain.c
@@ -15,6 +15,7 @@
#include <limits.h>
#include "access/parallel.h"
+#include "commands/dynamic_explain.h"
#include "commands/explain.h"
#include "commands/explain_format.h"
#include "commands/explain_state.h"
@@ -412,26 +413,9 @@ explain_ExecutorEnd(QueryDesc *queryDesc)
es->format = auto_explain_log_format;
es->settings = auto_explain_log_settings;
- ExplainBeginOutput(es);
- ExplainQueryText(es, queryDesc);
- ExplainQueryParameters(es, queryDesc->params, auto_explain_log_parameter_max_length);
- ExplainPrintPlan(es, queryDesc);
- if (es->analyze && auto_explain_log_triggers)
- ExplainPrintTriggers(es, queryDesc);
- if (es->costs)
- ExplainPrintJITSummary(es, queryDesc);
- ExplainEndOutput(es);
-
- /* Remove last line break */
- if (es->str->len > 0 && es->str->data[es->str->len - 1] == '\n')
- es->str->data[--es->str->len] = '\0';
-
- /* Fix JSON to output an object */
- if (auto_explain_log_format == EXPLAIN_FORMAT_JSON)
- {
- es->str->data[0] = '{';
- es->str->data[es->str->len - 1] = '}';
- }
+ ExplainStringAssemble(es, queryDesc, auto_explain_log_format,
+ auto_explain_log_triggers,
+ auto_explain_log_parameter_max_length);
/*
* Note: we rely on the existing logging of context or
diff --git a/doc/src/sgml/func.sgml b/doc/src/sgml/func.sgml
index 574a544d9f..13dc0a7745 100644
--- a/doc/src/sgml/func.sgml
+++ b/doc/src/sgml/func.sgml
@@ -28822,6 +28822,29 @@ acl | {postgres=arwdDxtm/postgres,foo=r/postgres}
</para></entry>
</row>
+ <row>
+ <entry role="func_table_entry"><para role="func_signature">
+ <indexterm>
+ <primary>pg_log_query_plan</primary>
+ </indexterm>
+ <function>pg_log_query_plan</function> ( <parameter>pid</parameter> <type>integer</type> )
+ <returnvalue>boolean</returnvalue>
+ </para>
+ <para>
+ Requests to log the plan of the query currently running on the
+ backend with specified process ID.
+ It will be logged at <literal>LOG</literal> message level and
+ will appear in the server log based on the log
+ configuration set (See <xref linkend="runtime-config-logging"/>
+ for more information), but will not be sent to the client
+ regardless of <xref linkend="guc-client-min-messages"/>.
+ </para>
+ <para>
+ This function is restricted to superusers by default, but other
+ users can be granted EXECUTE to run the function.
+ </para></entry>
+ </row>
+
<row>
<entry role="func_table_entry"><para role="func_signature">
<indexterm>
@@ -28972,6 +28995,38 @@ stats_timestamp | 2025-03-24 13:55:47.796698+01
will be less resource intensive when only the local backend is of interest.
</para>
</note>
+ </para>
+
+ <para>
+ <function>pg_log_query_plan</function> can be used
+ to log the plan of a backend process. For example:
+<programlisting>
+postgres=# SELECT pg_log_query_plan(201116);
+ pg_log_query_plan
+---------------------------
+ t
+(1 row)
+</programlisting>
+The format of the query plan is the same as when <literal>VERBOSE</literal>,
+<literal>COSTS</literal>, <literal>SETTINGS</literal> and
+<literal>FORMAT TEXT</literal> are used in the <command>EXPLAIN</command>
+command. For example:
+<screen>
+LOG: query plan running on backend with PID 201116 is:
+ Query Text: SELECT * FROM pgbench_accounts;
+ Seq Scan on public.pgbench_accounts (cost=0.00..52787.00 rows=2000000 width=97)
+ Output: aid, bid, abalance, filler
+ Settings: work_mem = '1MB'
+ Query Identifier: 8621255546560739680
+</screen>
+ Note that when the target is executing nested statements(statements executed
+ inside a function), only the innermost query plan is logged.
+ Note that logging plan may take some time, as it occurs when
+ the plan node is executed. For example, when a query is
+ running <function>pg_sleep</function>, the plan will not be
+ logged until the function execution completes.
+ Similarly, when a query is running under the extended query
+ protocol, the plan is logged only during the execute step.
</para>
</sect2>
diff --git a/src/backend/access/transam/xact.c b/src/backend/access/transam/xact.c
index b885513f76..b49edd2366 100644
--- a/src/backend/access/transam/xact.c
+++ b/src/backend/access/transam/xact.c
@@ -36,6 +36,7 @@
#include "catalog/pg_enum.h"
#include "catalog/storage.h"
#include "commands/async.h"
+#include "commands/dynamic_explain.h"
#include "commands/tablecmds.h"
#include "commands/trigger.h"
#include "common/pg_prng.h"
@@ -2904,6 +2905,9 @@ AbortTransaction(void)
/* Reset snapshot export state. */
SnapBuildResetExportedSnapshotState();
+ /* Reset pg_log_query_plan() related state. */
+ ResetLogQueryPlanState();
+
/*
* If this xact has started any unfinished parallel operation, clean up
* its workers and exit parallel mode. Don't warn about leaked resources.
@@ -5296,6 +5300,9 @@ AbortSubTransaction(void)
/* Reset logical streaming state. */
ResetLogicalStreamingState();
+ /* Reset pg_log_query_plan() related state. */
+ ResetLogQueryPlanState();
+
/*
* No need for SnapBuildResetExportedSnapshotState() here, snapshot
* exports are not supported in subtransactions.
diff --git a/src/backend/catalog/system_functions.sql b/src/backend/catalog/system_functions.sql
index 566f308e44..ec2e1c1fd9 100644
--- a/src/backend/catalog/system_functions.sql
+++ b/src/backend/catalog/system_functions.sql
@@ -775,6 +775,8 @@ REVOKE EXECUTE ON FUNCTION pg_ls_logicalmapdir() FROM PUBLIC;
REVOKE EXECUTE ON FUNCTION pg_ls_replslotdir(text) FROM PUBLIC;
+REVOKE EXECUTE ON FUNCTION pg_log_query_plan(integer) FROM PUBLIC;
+
--
-- We also set up some things as accessible to standard roles.
--
diff --git a/src/backend/commands/Makefile b/src/backend/commands/Makefile
index cb2fbdc7c6..5e83907eb1 100644
--- a/src/backend/commands/Makefile
+++ b/src/backend/commands/Makefile
@@ -32,6 +32,7 @@ OBJS = \
define.o \
discard.o \
dropcmds.o \
+ dynamic_explain.o \
event_trigger.o \
explain.o \
explain_dr.o \
diff --git a/src/backend/commands/dynamic_explain.c b/src/backend/commands/dynamic_explain.c
new file mode 100644
index 0000000000..d161aa8fa7
--- /dev/null
+++ b/src/backend/commands/dynamic_explain.c
@@ -0,0 +1,368 @@
+/*-------------------------------------------------------------------------
+ *
+ * dynamic_explain.c
+ * Explain query plans during execution
+ *
+ * Portions Copyright (c) 1996-2025, PostgreSQL Global Development Group
+ * Portions Copyright (c) 1994-5, Regents of the University of California
+ *
+ * IDENTIFICATION
+ * src/backend/commands/dynamic_explain.c
+ *
+ *-------------------------------------------------------------------------
+ */
+#include "postgres.h"
+#include "commands/dynamic_explain.h"
+#include "commands/explain.h"
+#include "commands/explain_format.h"
+#include "commands/explain_state.h"
+#include "miscadmin.h"
+#include "storage/proc.h"
+#include "storage/procarray.h"
+#include "utils/backend_status.h"
+
+/* Whether this backend is performing logging plan */
+static bool ProcessLogQueryPlanInterruptActive = false;
+
+/* Currently executing query's QueryDesc */
+static QueryDesc *ActiveQueryDesc = NULL;
+
+static TupleTableSlot *ExecProcNodeWithExplain(PlanState *ps);
+static void WrapExecProcNodeWithExplain(PlanState *ps);
+static void UnwrapExecProcNodeWithExplain(PlanState *ps);
+
+/*
+ * Handle receipt of an interrupt indicating logging the plan of the currently
+ * running query.
+ *
+ * All the actual work is deferred to ProcessLogQueryPlanInterrupt(),
+ * because we cannot safely emit a log message inside the signal handler.
+ */
+void
+HandleLogQueryPlanInterrupt(void)
+{
+ InterruptPending = true;
+ LogQueryPlanPending = true;
+ /* latch will be set by procsignal_sigusr1_handler */
+}
+
+/*
+ * Clear pg_log_query_plan() related state during (sub)transaction abort
+ */
+void
+ResetLogQueryPlanState(void)
+{
+ /*
+ * After abort, some elements of ActiveQueryDesc is freed. To avoid
+ * accessing them, reset ActiveQueryDesc here.
+ */
+ ActiveQueryDesc = NULL;
+ ProcessLogQueryPlanInterruptActive = false;
+}
+
+/*
+ * Wrap array of PlanState ExecProcNodes with ExecProcNodeWithExplain
+ */
+static void
+WrapPlanStatesWithExplain(PlanState **planstates, int nplans)
+{
+ int i;
+
+ for (i = 0; i < nplans; i++)
+ WrapExecProcNodeWithExplain(planstates[i]);
+}
+
+/*
+ * Wrap CustomScanState children's ExecProcNodes with ExecProcNodeWithExplain
+ */
+static void
+WrapCustomPlanChildWithExplain(CustomScanState *css)
+{
+ ListCell *cell;
+
+ foreach(cell, css->custom_ps)
+ WrapExecProcNodeWithExplain((PlanState *) lfirst(cell));
+}
+
+/*
+ * Wrap ExecProcNode with ExecProcNodeWithExplain recursively
+ */
+static void
+WrapExecProcNodeWithExplain(PlanState *ps)
+{
+ /* wrapping can be done only once */
+ if (ps->ExecProcNodeOriginal != NULL)
+ return;
+
+ check_stack_depth();
+
+ ps->ExecProcNodeOriginal = ps->ExecProcNode;
+ ps->ExecProcNode = ExecProcNodeWithExplain;
+
+ if (ps->lefttree != NULL)
+ WrapExecProcNodeWithExplain(ps->lefttree);
+ if (ps->righttree != NULL)
+ WrapExecProcNodeWithExplain(ps->righttree);
+ if (ps->subPlan != NULL)
+ {
+ ListCell *l;
+
+ foreach(l, ps->subPlan)
+ {
+ SubPlanState *sstate = (SubPlanState *) lfirst(l);
+
+ WrapExecProcNodeWithExplain(sstate->planstate);
+ }
+ }
+
+ /* special child plans */
+ switch (nodeTag(ps->plan))
+ {
+ case T_Append:
+ WrapPlanStatesWithExplain(((AppendState *) ps)->appendplans,
+ ((AppendState *) ps)->as_nplans);
+ break;
+ case T_MergeAppend:
+ WrapPlanStatesWithExplain(((MergeAppendState *) ps)->mergeplans,
+ ((MergeAppendState *) ps)->ms_nplans);
+ break;
+ case T_BitmapAnd:
+ WrapPlanStatesWithExplain(((BitmapAndState *) ps)->bitmapplans,
+ ((BitmapAndState *) ps)->nplans);
+ break;
+ case T_BitmapOr:
+ WrapPlanStatesWithExplain(((BitmapOrState *) ps)->bitmapplans,
+ ((BitmapOrState *) ps)->nplans);
+ break;
+ case T_SubqueryScan:
+ WrapExecProcNodeWithExplain(((SubqueryScanState *) ps)->subplan);
+ break;
+ case T_CustomScan:
+ WrapCustomPlanChildWithExplain((CustomScanState *) ps);
+ break;
+ default:
+ break;
+ }
+}
+
+/*
+ * Unwrap array of PlanStates ExecProcNodes with ExecProcNodeWithExplain
+ */
+static void
+UnwrapPlanStatesWithExplain(PlanState **planstates, int nplans)
+{
+ int i;
+
+ for (i = 0; i < nplans; i++)
+ UnwrapExecProcNodeWithExplain(planstates[i]);
+}
+
+/*
+ * Unwrap CustomScanState children's ExecProcNodes with ExecProcNodeWithExplain
+ */
+static void
+UnwrapCustomPlanChildWithExplain(CustomScanState *css)
+{
+ ListCell *cell;
+
+ foreach(cell, css->custom_ps)
+ UnwrapExecProcNodeWithExplain((PlanState *) lfirst(cell));
+}
+
+/*
+ * Unwrap ExecProcNode with ExecProcNodeWithExplain recursively
+ */
+static void
+UnwrapExecProcNodeWithExplain(PlanState *ps)
+{
+ Assert(ps->ExecProcNodeOriginal != NULL);
+
+ check_stack_depth();
+
+ ps->ExecProcNode = ps->ExecProcNodeOriginal;
+ ps->ExecProcNodeOriginal = NULL;
+
+ if (ps->lefttree != NULL)
+ UnwrapExecProcNodeWithExplain(ps->lefttree);
+ if (ps->righttree != NULL)
+ UnwrapExecProcNodeWithExplain(ps->righttree);
+ if (ps->subPlan != NULL)
+ {
+ ListCell *l;
+
+ foreach(l, ps->subPlan)
+ {
+ SubPlanState *sstate = (SubPlanState *) lfirst(l);
+
+ UnwrapExecProcNodeWithExplain(sstate->planstate);
+ }
+ }
+
+ /* special child plans */
+ switch (nodeTag(ps->plan))
+ {
+ case T_Append:
+ UnwrapPlanStatesWithExplain(((AppendState *) ps)->appendplans,
+ ((AppendState *) ps)->as_nplans);
+ break;
+ case T_MergeAppend:
+ UnwrapPlanStatesWithExplain(((MergeAppendState *) ps)->mergeplans,
+ ((MergeAppendState *) ps)->ms_nplans);
+ break;
+ case T_BitmapAnd:
+ UnwrapPlanStatesWithExplain(((BitmapAndState *) ps)->bitmapplans,
+ ((BitmapAndState *) ps)->nplans);
+ break;
+ case T_BitmapOr:
+ UnwrapPlanStatesWithExplain(((BitmapOrState *) ps)->bitmapplans,
+ ((BitmapOrState *) ps)->nplans);
+ break;
+ case T_SubqueryScan:
+ UnwrapExecProcNodeWithExplain(((SubqueryScanState *) ps)->subplan);
+ break;
+ case T_CustomScan:
+ UnwrapCustomPlanChildWithExplain((CustomScanState *) ps);
+ break;
+ default:
+ break;
+ }
+}
+
+/*
+ * Wrap ExecProcNode with codes which logs currently running plan
+ */
+static TupleTableSlot *
+ExecProcNodeWithExplain(PlanState *ps)
+{
+ ExplainState *es;
+ MemoryContext cxt;
+ MemoryContext old_cxt;
+
+ check_stack_depth();
+
+ cxt = AllocSetContextCreate(CurrentMemoryContext,
+ "log_query_plan temporary context",
+ ALLOCSET_DEFAULT_SIZES);
+
+ old_cxt = MemoryContextSwitchTo(cxt);
+
+ es = NewExplainState();
+
+ es->format = EXPLAIN_FORMAT_TEXT;
+ es->settings = true;
+ es->verbose = true;
+ es->signaled = true;
+
+ ExplainStringAssemble(es, ActiveQueryDesc, es->format, 0, -1);
+
+ ereport(LOG_SERVER_ONLY,
+ errmsg("query plan running on backend with PID %d is:\n%s",
+ MyProcPid, es->str->data),
+ errhidestmt(true),
+ errhidecontext(true));
+
+ MemoryContextSwitchTo(old_cxt);
+ MemoryContextDelete(cxt);
+
+ UnwrapExecProcNodeWithExplain(ActiveQueryDesc->planstate);
+
+ /*
+ * Since unwrapping has already done, call ExecProcNode() not
+ * ExecProcNodeOriginal().
+ */
+ return ps->ExecProcNode(ps);
+}
+
+/*
+ * Add wrapper which logs explain of the plan to ExecProcNode
+ *
+ * Since running EXPLAIN codes at any arbitrary CHECK_FOR_INTERRUPTS() is
+ * unsafe, this function just wraps every ExecProcNode.
+ * In this way, EXPLAIN code is only executed at the timing of ExecProcNode,
+ * which seems safe.
+ */
+void
+ProcessLogQueryPlanInterrupt(void)
+{
+ LogQueryPlanPending = false;
+
+ /* Cannot re-enter */
+ if (ProcessLogQueryPlanInterruptActive)
+ return;
+
+ ProcessLogQueryPlanInterruptActive = true;
+
+ if (ActiveQueryDesc == NULL)
+ {
+ ereport(LOG_SERVER_ONLY,
+ errmsg("backend with PID %d is not running a query or a subtransaction is aborted",
+ MyProcPid),
+ errhidestmt(true),
+ errhidecontext(true));
+
+ ProcessLogQueryPlanInterruptActive = false;
+ return;
+ }
+
+ WrapExecProcNodeWithExplain(ActiveQueryDesc->planstate);
+ ProcessLogQueryPlanInterruptActive = false;
+}
+
+QueryDesc *
+GetActiveQueryDesc(void)
+{
+ return ActiveQueryDesc;
+}
+
+void
+SetActiveQueryDesc(QueryDesc *queryDesc)
+{
+ ActiveQueryDesc = queryDesc;
+}
+
+/*
+ * Signal a backend process to log the query plan of the running query.
+ *
+ * By default, only superusers are allowed to signal to log the plan because
+ * allowing any users to issue this request at an unbounded rate would
+ * cause lots of log messages and which can lead to denial of service.
+ * Additional roles can be permitted with GRANT.
+ */
+Datum
+pg_log_query_plan(PG_FUNCTION_ARGS)
+{
+ int pid = PG_GETARG_INT32(0);
+ PGPROC *proc;
+ PgBackendStatus *be_status;
+
+ proc = BackendPidGetProc(pid);
+
+ if (proc == NULL)
+ {
+ /*
+ * This is just a warning so a loop-through-resultset will not abort
+ * if one backend terminated on its own during the run.
+ */
+ ereport(WARNING,
+ (errmsg("PID %d is not a PostgreSQL backend process", pid)));
+ PG_RETURN_BOOL(false);
+ }
+
+ be_status = pgstat_get_beentry_by_proc_number(proc->vxid.procNumber);
+ if (be_status->st_backendType != B_BACKEND)
+ {
+ ereport(WARNING,
+ (errmsg("PID %d is not a PostgreSQL client backend process", pid)));
+ PG_RETURN_BOOL(false);
+ }
+
+ if (SendProcSignal(pid, PROCSIG_LOG_QUERY_PLAN, proc->vxid.procNumber) < 0)
+ {
+ /* Again, just a warning to allow loops */
+ ereport(WARNING,
+ (errmsg("could not send signal to process %d: %m", pid)));
+ PG_RETURN_BOOL(false);
+ }
+
+ PG_RETURN_BOOL(true);
+}
diff --git a/src/backend/commands/explain.c b/src/backend/commands/explain.c
index 786ee865f1..fd37772504 100644
--- a/src/backend/commands/explain.c
+++ b/src/backend/commands/explain.c
@@ -1100,6 +1100,37 @@ ExplainQueryParameters(ExplainState *es, ParamListInfo params, int maxlen)
ExplainPropertyText("Query Parameters", str, es);
}
+/*
+ * ExplainStringAssemble -
+ * Assemble es->str for logging according to specified options and format
+ */
+
+void
+ExplainStringAssemble(ExplainState *es, QueryDesc *queryDesc, int logFormat,
+ bool logTriggers, int logParameterMaxLength)
+{
+ ExplainBeginOutput(es);
+ ExplainQueryText(es, queryDesc);
+ ExplainQueryParameters(es, queryDesc->params, logParameterMaxLength);
+ ExplainPrintPlan(es, queryDesc);
+ if (es->analyze && logTriggers)
+ ExplainPrintTriggers(es, queryDesc);
+ if (es->costs)
+ ExplainPrintJITSummary(es, queryDesc);
+ ExplainEndOutput(es);
+
+ /* Remove last line break */
+ if (es->str->len > 0 && es->str->data[es->str->len - 1] == '\n')
+ es->str->data[--es->str->len] = '\0';
+
+ /* Fix JSON to output an object */
+ if (logFormat == EXPLAIN_FORMAT_JSON)
+ {
+ es->str->data[0] = '{';
+ es->str->data[es->str->len - 1] = '}';
+ }
+}
+
/*
* report_triggers -
* report execution stats for a single relation's triggers
@@ -1827,7 +1858,10 @@ ExplainNode(PlanState *planstate, List *ancestors,
/*
* We have to forcibly clean up the instrumentation state because we
- * haven't done ExecutorEnd yet. This is pretty grotty ...
+ * haven't done ExecutorEnd yet. This is pretty grotty ... This cleanup
+ * should not be done when the query has already been executed and explain
+ * has been called by signal, as the target query may use instrumentation
+ * and clean itself up.
*
* Note: contrib/auto_explain could cause instrumentation to be set up
* even though we didn't ask for it here. Be careful not to print any
@@ -1835,7 +1869,7 @@ ExplainNode(PlanState *planstate, List *ancestors,
* InstrEndLoop call anyway, if possible, to reduce the number of cases
* auto_explain has to contend with.
*/
- if (planstate->instrument)
+ if (planstate->instrument && !es->signaled)
InstrEndLoop(planstate->instrument);
if (es->analyze &&
diff --git a/src/backend/commands/meson.build b/src/backend/commands/meson.build
index dd4cde41d3..4a64b8e9d0 100644
--- a/src/backend/commands/meson.build
+++ b/src/backend/commands/meson.build
@@ -20,6 +20,7 @@ backend_sources += files(
'define.c',
'discard.c',
'dropcmds.c',
+ 'dynamic_explain.c',
'event_trigger.c',
'explain.c',
'explain_dr.c',
diff --git a/src/backend/executor/execMain.c b/src/backend/executor/execMain.c
index 7230f96810..b1f3e83b62 100644
--- a/src/backend/executor/execMain.c
+++ b/src/backend/executor/execMain.c
@@ -43,6 +43,7 @@
#include "access/xact.h"
#include "catalog/namespace.h"
#include "catalog/partition.h"
+#include "commands/dynamic_explain.h"
#include "commands/matview.h"
#include "commands/trigger.h"
#include "executor/executor.h"
@@ -380,6 +381,7 @@ standard_ExecutorRun(QueryDesc *queryDesc,
DestReceiver *dest;
bool sendTuples;
MemoryContext oldcontext;
+ QueryDesc *oldActiveQueryDesc;
/* sanity checks */
Assert(queryDesc != NULL);
@@ -393,6 +395,13 @@ standard_ExecutorRun(QueryDesc *queryDesc,
/* caller must ensure the query's snapshot is active */
Assert(GetActiveSnapshot() == estate->es_snapshot);
+ /*
+ * Save ActiveQueryDesc here to enable retrieval of the currently running
+ * queryDesc for nested queries.
+ */
+ oldActiveQueryDesc = GetActiveQueryDesc();
+ SetActiveQueryDesc(queryDesc);
+
/*
* Switch into per-query memory context
*/
@@ -455,6 +464,7 @@ standard_ExecutorRun(QueryDesc *queryDesc,
InstrStopNode(queryDesc->totaltime, estate->es_processed);
MemoryContextSwitchTo(oldcontext);
+ SetActiveQueryDesc(oldActiveQueryDesc);
}
/* ----------------------------------------------------------------
diff --git a/src/backend/storage/ipc/procsignal.c b/src/backend/storage/ipc/procsignal.c
index a3c2cd1227..d242bedcbb 100644
--- a/src/backend/storage/ipc/procsignal.c
+++ b/src/backend/storage/ipc/procsignal.c
@@ -19,6 +19,7 @@
#include "access/parallel.h"
#include "commands/async.h"
+#include "commands/dynamic_explain.h"
#include "miscadmin.h"
#include "pgstat.h"
#include "port/pg_bitutils.h"
@@ -693,6 +694,9 @@ procsignal_sigusr1_handler(SIGNAL_ARGS)
if (CheckProcSignal(PROCSIG_GET_MEMORY_CONTEXT))
HandleGetMemoryContextInterrupt();
+ if (CheckProcSignal(PROCSIG_LOG_QUERY_PLAN))
+ HandleLogQueryPlanInterrupt();
+
if (CheckProcSignal(PROCSIG_PARALLEL_APPLY_MESSAGE))
HandleParallelApplyMessageInterrupt();
diff --git a/src/backend/tcop/postgres.c b/src/backend/tcop/postgres.c
index dc4c600922..9be814b16e 100644
--- a/src/backend/tcop/postgres.c
+++ b/src/backend/tcop/postgres.c
@@ -37,6 +37,7 @@
#include "catalog/pg_type.h"
#include "commands/async.h"
#include "commands/event_trigger.h"
+#include "commands/dynamic_explain.h"
#include "commands/prepare.h"
#include "common/pg_prng.h"
#include "jit/jit.h"
@@ -3538,6 +3539,9 @@ ProcessInterrupts(void)
if (PublishMemoryContextPending)
ProcessGetMemoryContextInterrupt();
+ if (LogQueryPlanPending)
+ ProcessLogQueryPlanInterrupt();
+
if (ParallelApplyMessagePending)
ProcessParallelApplyMessages();
}
diff --git a/src/backend/utils/init/globals.c b/src/backend/utils/init/globals.c
index 1847e7c85d..ae5bd851f3 100644
--- a/src/backend/utils/init/globals.c
+++ b/src/backend/utils/init/globals.c
@@ -41,6 +41,8 @@ volatile sig_atomic_t ProcSignalBarrierPending = false;
volatile sig_atomic_t LogMemoryContextPending = false;
volatile sig_atomic_t PublishMemoryContextPending = false;
volatile sig_atomic_t IdleStatsUpdateTimeoutPending = false;
+volatile sig_atomic_t LogQueryPlanPending = false;
+
volatile uint32 InterruptHoldoffCount = 0;
volatile uint32 QueryCancelHoldoffCount = 0;
volatile uint32 CritSectionCount = 0;
diff --git a/src/include/catalog/pg_proc.dat b/src/include/catalog/pg_proc.dat
index 62beb71da2..ae793299e2 100644
--- a/src/include/catalog/pg_proc.dat
+++ b/src/include/catalog/pg_proc.dat
@@ -8581,6 +8581,12 @@
proargnames => '{pid, summary, timeout, name, ident, type, path, level, total_bytes, total_nblocks, free_bytes, free_chunks, used_bytes, num_agg_contexts, stats_timestamp}',
prosrc => 'pg_get_process_memory_contexts' },
+# logging plan of the running query on the specified backend
+{ oid => '8000', descr => 'log plan of the running query on the specified backend',
+ proname => 'pg_log_query_plan',
+ provolatile => 'v', prorettype => 'bool',
+ proargtypes => 'int4', prosrc => 'pg_log_query_plan' },
+
# non-persistent series generator
{ oid => '1066', descr => 'non-persistent series generator',
proname => 'generate_series', prorows => '1000',
diff --git a/src/include/commands/dynamic_explain.h b/src/include/commands/dynamic_explain.h
new file mode 100644
index 0000000000..68b16ec9be
--- /dev/null
+++ b/src/include/commands/dynamic_explain.h
@@ -0,0 +1,26 @@
+/*-------------------------------------------------------------------------
+ *
+ * dynamic_explain.h
+ * prototypes for dynamic_explain.c
+ *
+ * Portions Copyright (c) 1996-2025, PostgreSQL Global Development Group
+ * Portions Copyright (c) 1994-5, Regents of the University of California
+ *
+ * src/include/commands/dynamic_explain.h
+ *
+ *-------------------------------------------------------------------------
+ */
+#ifndef DYNAMIC_EXPLAIN_H
+#define DYNAMIC_EXPLAIN_H
+
+#include "executor/executor.h"
+#include "commands/explain_state.h"
+
+extern void HandleLogQueryPlanInterrupt(void);
+extern void ResetLogQueryPlanState(void);
+extern void ProcessLogQueryPlanInterrupt(void);
+extern QueryDesc *GetActiveQueryDesc(void);
+extern void SetActiveQueryDesc(QueryDesc *queryDesc);
+extern Datum pg_log_query_plan(PG_FUNCTION_ARGS);
+
+#endif /* DYNAMIC_EXPLAIN_H */
diff --git a/src/include/commands/explain.h b/src/include/commands/explain.h
index 03c5b3d73e..083567caf0 100644
--- a/src/include/commands/explain.h
+++ b/src/include/commands/explain.h
@@ -72,6 +72,8 @@ extern void ExplainOnePlan(PlannedStmt *plannedstmt, CachedPlan *cplan,
const BufferUsage *bufusage,
const MemoryContextCounters *mem_counters);
+extern void ExplainPrintPlan(struct ExplainState *es, QueryDesc *queryDesc);
+extern void ExplainPrintTriggers(struct ExplainState *es, QueryDesc *queryDesc);
extern void ExplainPrintPlan(struct ExplainState *es, QueryDesc *queryDesc);
extern void ExplainPrintTriggers(struct ExplainState *es,
QueryDesc *queryDesc);
@@ -82,5 +84,8 @@ extern void ExplainPrintJITSummary(struct ExplainState *es,
extern void ExplainQueryText(struct ExplainState *es, QueryDesc *queryDesc);
extern void ExplainQueryParameters(struct ExplainState *es,
ParamListInfo params, int maxlen);
+extern void ExplainStringAssemble(struct ExplainState *es, QueryDesc *queryDesc,
+ int logFormat, bool logTriggers,
+ int logParameterMaxLength);
#endif /* EXPLAIN_H */
diff --git a/src/include/commands/explain_state.h b/src/include/commands/explain_state.h
index 32728f5d1a..fcef956396 100644
--- a/src/include/commands/explain_state.h
+++ b/src/include/commands/explain_state.h
@@ -71,6 +71,7 @@ typedef struct ExplainState
* entry */
/* state related to the current plan node */
ExplainWorkersState *workers_state; /* needed if parallel plan */
+ bool signaled; /* whether explain is called by signal */
/* extensions */
void **extension_state;
int extension_state_allocated;
diff --git a/src/include/miscadmin.h b/src/include/miscadmin.h
index 72f5655fb3..49412a9cb4 100644
--- a/src/include/miscadmin.h
+++ b/src/include/miscadmin.h
@@ -97,6 +97,7 @@ extern PGDLLIMPORT volatile sig_atomic_t ProcSignalBarrierPending;
extern PGDLLIMPORT volatile sig_atomic_t LogMemoryContextPending;
extern PGDLLIMPORT volatile sig_atomic_t IdleStatsUpdateTimeoutPending;
extern PGDLLIMPORT volatile sig_atomic_t PublishMemoryContextPending;
+extern PGDLLIMPORT volatile sig_atomic_t LogQueryPlanPending;
extern PGDLLIMPORT volatile sig_atomic_t CheckClientConnectionPending;
extern PGDLLIMPORT volatile sig_atomic_t ClientConnectionLost;
diff --git a/src/include/nodes/execnodes.h b/src/include/nodes/execnodes.h
index 5b6cadb5a6..feb29a3818 100644
--- a/src/include/nodes/execnodes.h
+++ b/src/include/nodes/execnodes.h
@@ -1166,6 +1166,9 @@ typedef struct PlanState
ExecProcNodeMtd ExecProcNodeReal; /* actual function, if above is a
* wrapper */
+ ExecProcNodeMtd ExecProcNodeOriginal; /* temporary place when adding
+ * process for ExecProcNode */
+
Instrumentation *instrument; /* Optional runtime stats for this node */
WorkerInstrumentation *worker_instrument; /* per-worker instrumentation */
diff --git a/src/include/storage/procsignal.h b/src/include/storage/procsignal.h
index cfe1463144..82cfcaccaa 100644
--- a/src/include/storage/procsignal.h
+++ b/src/include/storage/procsignal.h
@@ -36,6 +36,8 @@ typedef enum
PROCSIG_BARRIER, /* global barrier interrupt */
PROCSIG_LOG_MEMORY_CONTEXT, /* ask backend to log the memory contexts */
PROCSIG_GET_MEMORY_CONTEXT, /* ask backend to send the memory contexts */
+ PROCSIG_LOG_QUERY_PLAN, /* ask backend to log plan of the current
+ * query */
PROCSIG_PARALLEL_APPLY_MESSAGE, /* Message from parallel apply workers */
/* Recovery conflict reasons */
diff --git a/src/include/tcop/pquery.h b/src/include/tcop/pquery.h
index fa3cc5f2df..7949abf76b 100644
--- a/src/include/tcop/pquery.h
+++ b/src/include/tcop/pquery.h
@@ -22,7 +22,6 @@ struct PlannedStmt; /* avoid including plannodes.h here */
extern PGDLLIMPORT Portal ActivePortal;
-
extern PortalStrategy ChoosePortalStrategy(List *stmts);
extern List *FetchPortalTargetList(Portal portal);
diff --git a/src/test/regress/expected/misc_functions.out b/src/test/regress/expected/misc_functions.out
index d3f5d16a67..7dcb9951e7 100644
--- a/src/test/regress/expected/misc_functions.out
+++ b/src/test/regress/expected/misc_functions.out
@@ -316,14 +316,15 @@ SELECT test_canonicalize_path('./abc/./def/.././ghi/../../../jkl/mno');
../jkl/mno
(1 row)
+-- Test logging functions
--
--- pg_log_backend_memory_contexts()
---
--- Memory contexts are logged and they are not returned to the function.
+-- The outputs of these functions are logged and they are not returned to
+-- the function.
-- Furthermore, their contents can vary depending on the timing. However,
-- we can at least verify that the code doesn't fail, and that the
-- permissions are set properly.
--
+-- pg_log_backend_memory_contexts()
SELECT pg_log_backend_memory_contexts(pg_backend_pid());
pg_log_backend_memory_contexts
--------------------------------
@@ -337,8 +338,8 @@ SELECT pg_log_backend_memory_contexts(pid) FROM pg_stat_activity
t
(1 row)
-CREATE ROLE regress_log_memory;
-SELECT has_function_privilege('regress_log_memory',
+CREATE ROLE regress_log_function;
+SELECT has_function_privilege('regress_log_function',
'pg_log_backend_memory_contexts(integer)', 'EXECUTE'); -- no
has_function_privilege
------------------------
@@ -346,15 +347,15 @@ SELECT has_function_privilege('regress_log_memory',
(1 row)
GRANT EXECUTE ON FUNCTION pg_log_backend_memory_contexts(integer)
- TO regress_log_memory;
-SELECT has_function_privilege('regress_log_memory',
+ TO regress_log_function;
+SELECT has_function_privilege('regress_log_function',
'pg_log_backend_memory_contexts(integer)', 'EXECUTE'); -- yes
has_function_privilege
------------------------
t
(1 row)
-SET ROLE regress_log_memory;
+SET ROLE regress_log_function;
SELECT pg_log_backend_memory_contexts(pg_backend_pid());
pg_log_backend_memory_contexts
--------------------------------
@@ -363,8 +364,41 @@ SELECT pg_log_backend_memory_contexts(pg_backend_pid());
RESET ROLE;
REVOKE EXECUTE ON FUNCTION pg_log_backend_memory_contexts(integer)
- FROM regress_log_memory;
-DROP ROLE regress_log_memory;
+ FROM regress_log_function;
+-- pg_log_query_plan()
+SELECT pg_log_query_plan(pg_backend_pid());
+ pg_log_query_plan
+-------------------
+ t
+(1 row)
+
+SELECT has_function_privilege('regress_log_function',
+ 'pg_log_query_plan(integer)', 'EXECUTE'); -- no
+ has_function_privilege
+------------------------
+ f
+(1 row)
+
+GRANT EXECUTE ON FUNCTION pg_log_query_plan(integer)
+ TO regress_log_function;
+SELECT has_function_privilege('regress_log_function',
+ 'pg_log_query_plan(integer)', 'EXECUTE'); -- yes
+ has_function_privilege
+------------------------
+ t
+(1 row)
+
+SET ROLE regress_log_function;
+SELECT pg_log_query_plan(pg_backend_pid());
+ pg_log_query_plan
+-------------------
+ t
+(1 row)
+
+RESET ROLE;
+REVOKE EXECUTE ON FUNCTION pg_log_query_plan(integer)
+ FROM regress_log_function;
+DROP ROLE regress_log_function;
--
-- Test some built-in SRFs
--
diff --git a/src/test/regress/sql/misc_functions.sql b/src/test/regress/sql/misc_functions.sql
index aaebb29833..92330355f6 100644
--- a/src/test/regress/sql/misc_functions.sql
+++ b/src/test/regress/sql/misc_functions.sql
@@ -109,39 +109,60 @@ SELECT test_canonicalize_path('./abc/./def/.');
SELECT test_canonicalize_path('./abc/././def/.');
SELECT test_canonicalize_path('./abc/./def/.././ghi/../../../jkl/mno');
+-- Test logging functions
--
--- pg_log_backend_memory_contexts()
---
--- Memory contexts are logged and they are not returned to the function.
+-- The outputs of these functions are logged and they are not returned to
+-- the function.
-- Furthermore, their contents can vary depending on the timing. However,
-- we can at least verify that the code doesn't fail, and that the
-- permissions are set properly.
--
+-- pg_log_backend_memory_contexts()
+
SELECT pg_log_backend_memory_contexts(pg_backend_pid());
SELECT pg_log_backend_memory_contexts(pid) FROM pg_stat_activity
WHERE backend_type = 'checkpointer';
-CREATE ROLE regress_log_memory;
+CREATE ROLE regress_log_function;
-SELECT has_function_privilege('regress_log_memory',
+SELECT has_function_privilege('regress_log_function',
'pg_log_backend_memory_contexts(integer)', 'EXECUTE'); -- no
GRANT EXECUTE ON FUNCTION pg_log_backend_memory_contexts(integer)
- TO regress_log_memory;
+ TO regress_log_function;
-SELECT has_function_privilege('regress_log_memory',
+SELECT has_function_privilege('regress_log_function',
'pg_log_backend_memory_contexts(integer)', 'EXECUTE'); -- yes
-SET ROLE regress_log_memory;
+SET ROLE regress_log_function;
SELECT pg_log_backend_memory_contexts(pg_backend_pid());
RESET ROLE;
REVOKE EXECUTE ON FUNCTION pg_log_backend_memory_contexts(integer)
- FROM regress_log_memory;
+ FROM regress_log_function;
+
+-- pg_log_query_plan()
+SELECT pg_log_query_plan(pg_backend_pid());
+
+SELECT has_function_privilege('regress_log_function',
+ 'pg_log_query_plan(integer)', 'EXECUTE'); -- no
+
+GRANT EXECUTE ON FUNCTION pg_log_query_plan(integer)
+ TO regress_log_function;
+
+SELECT has_function_privilege('regress_log_function',
+ 'pg_log_query_plan(integer)', 'EXECUTE'); -- yes
+
+SET ROLE regress_log_function;
+SELECT pg_log_query_plan(pg_backend_pid());
+RESET ROLE;
+
+REVOKE EXECUTE ON FUNCTION pg_log_query_plan(integer)
+ FROM regress_log_function;
-DROP ROLE regress_log_memory;
+DROP ROLE regress_log_function;
--
-- Test some built-in SRFs
base-commit: 3631612eae9c2def99151c4f36b1b3771f53cba7
--
2.48.1
