Allow plugins to set a 64-bit plan identifier in PlannedStmt

This field can be optionally set in a PlannedStmt through the planner
hook, giving extensions the possibility to assign an identifier related
to a computed plan.  The backend is changed to report it in the backend
entry of a process running (including the extended query protocol), with
semantics and APIs to set or get it similar to what is used for the
existing query ID (introduced in the backend via 4f0b0966c8).  The plan
ID is reset at the same timing as the query ID.  Currently, this
information is not added to the system view pg_stat_activity; extensions
can access it through PgBackendStatus.

Some patches have been proposed to provide some features in the planning
area, where a plan identifier is used as a key to know the plan involved
(for statistics, plan storage and manipulations, etc.), and the point of
this commit is to provide an anchor in the backend that extensions can
rely on for future work.   The reset of the plan identifier is
controlled by core and follows the same pattern as the query identifier
added in 4f0b0966c8.

The contents of this commit are extracted from a larger set proposed
originally by Lukas Fittl, that Sami Imseih has proposed as an
independent change, with a few tweaks sprinkled by me.

Author: Lukas Fittl <lukas@fittl.com>
Author: Sami Imseih <samimseih@gmail.com>
Reviewed-by: Bertrand Drouvot <bertranddrouvot.pg@gmail.com>
Reviewed-by: Michael Paquier <michael@paquier.xyz>
Discussion: https://postgr.es/m/CAP53Pkyow59ajFMHGpmb1BK9WHDypaWtUsS_5DoYUEfsa_Hktg@mail.gmail.com
Discussion: https://postgr.es/m/CAA5RZ0vyWd4r35uUBUmhngv8XqeiJUkJDDKkLf5LCoWxv-t_pw@mail.gmail.com

diff --git a/src/backend/executor/execParallel.c b/src/backend/executor/execParallel.c
index e9337a97d174edac8b8eaab978da988957ac609f..39c990ae638d5b1f9e3fc32bd5e33daf3308aff0 100644 (file)
--- a/src/backend/executor/execParallel.c
+++ b/src/backend/executor/execParallel.c
@@ -175,6 +175,7 @@ ExecSerializePlan(Plan *plan, EState *estate)
    pstmt = makeNode(PlannedStmt);
    pstmt->commandType = CMD_SELECT;
    pstmt->queryId = pgstat_get_my_query_id();
+   pstmt->planId = pgstat_get_my_plan_id();
    pstmt->hasReturning = false;
    pstmt->hasModifyingCTE = false;
    pstmt->canSetTag = true;

diff --git a/src/backend/optimizer/plan/planner.c b/src/backend/optimizer/plan/planner.c
index 141177e74135c33686993b454a73790635864ad6..566ce5b3cb40f30b94f60d049b78239cfa9e3b55 100644 (file)
--- a/src/backend/optimizer/plan/planner.c
+++ b/src/backend/optimizer/plan/planner.c
@@ -58,6 +58,7 @@
 #include "parser/parsetree.h"
 #include "partitioning/partdesc.h"
 #include "rewrite/rewriteManip.h"
+#include "utils/backend_status.h"
 #include "utils/lsyscache.h"
 #include "utils/rel.h"
 #include "utils/selfuncs.h"
@@ -291,6 +292,9 @@ planner(Query *parse, const char *query_string, int cursorOptions,
        result = (*planner_hook) (parse, query_string, cursorOptions, boundParams);
    else
        result = standard_planner(parse, query_string, cursorOptions, boundParams);
+
+   pgstat_report_plan_id(result->planId, false);
+
    return result;
 }
 

diff --git a/src/backend/tcop/postgres.c b/src/backend/tcop/postgres.c
index 0554a4ae3c7b068cdfdf3b5042d469fc34609133..4d2edb10658bea9b572196f25535360adc0ac15b 100644 (file)
--- a/src/backend/tcop/postgres.c
+++ b/src/backend/tcop/postgres.c
@@ -1107,6 +1107,7 @@ exec_simple_query(const char *query_string)
        size_t      cmdtaglen;
 
        pgstat_report_query_id(0, true);
+       pgstat_report_plan_id(0, true);
 
        /*
         * Get the command name for use in status display (it also becomes the
@@ -2030,6 +2031,18 @@ exec_bind_message(StringInfo input_message)
                      cplan,
                      psrc);
 
+   /* Portal is defined, set the plan ID based on its contents. */
+   foreach(lc, portal->stmts)
+   {
+       PlannedStmt *plan = lfirst_node(PlannedStmt, lc);
+
+       if (plan->planId != UINT64CONST(0))
+       {
+           pgstat_report_plan_id(plan->planId, false);
+           break;
+       }
+   }
+
    /* Done with the snapshot used for parameter I/O and parsing/planning */
    if (snapshot_set)
        PopActiveSnapshot();
@@ -2170,6 +2183,17 @@ exec_execute_message(const char *portal_name, long max_rows)
        }
    }
 
+   foreach(lc, portal->stmts)
+   {
+       PlannedStmt *stmt = lfirst_node(PlannedStmt, lc);
+
+       if (stmt->planId != UINT64CONST(0))
+       {
+           pgstat_report_plan_id(stmt->planId, false);
+           break;
+       }
+   }
+
    cmdtagname = GetCommandTagNameAndLen(portal->commandTag, &cmdtaglen);
 
    set_ps_display_with_len(cmdtagname, cmdtaglen);

diff --git a/src/backend/utils/activity/backend_status.c b/src/backend/utils/activity/backend_status.c
index 7681b4ba5a99803e1424e6cfadb5ed7085c65f56..e1576e64b6d4c3547c66f64dc149bf04bb080f80 100644 (file)
--- a/src/backend/utils/activity/backend_status.c
+++ b/src/backend/utils/activity/backend_status.c
@@ -321,6 +321,7 @@ pgstat_bestart_initial(void)
    lbeentry.st_progress_command = PROGRESS_COMMAND_INVALID;
    lbeentry.st_progress_command_target = InvalidOid;
    lbeentry.st_query_id = UINT64CONST(0);
+   lbeentry.st_plan_id = UINT64CONST(0);
 
    /*
     * we don't zero st_progress_param here to save cycles; nobody should
@@ -599,6 +600,7 @@ pgstat_report_activity(BackendState state, const char *cmd_str)
            /* st_xact_start_timestamp and wait_event_info are also disabled */
            beentry->st_xact_start_timestamp = 0;
            beentry->st_query_id = UINT64CONST(0);
+           beentry->st_plan_id = UINT64CONST(0);
            proc->wait_event_info = 0;
            PGSTAT_END_WRITE_ACTIVITY(beentry);
        }
@@ -659,7 +661,10 @@ pgstat_report_activity(BackendState state, const char *cmd_str)
     * identifier.
     */
    if (state == STATE_RUNNING)
+   {
        beentry->st_query_id = UINT64CONST(0);
+       beentry->st_plan_id = UINT64CONST(0);
+   }
 
    if (cmd_str != NULL)
    {
@@ -710,6 +715,44 @@ pgstat_report_query_id(uint64 query_id, bool force)
    PGSTAT_END_WRITE_ACTIVITY(beentry);
 }
 
+/* --------
+ * pgstat_report_plan_id() -
+ *
+ * Called to update top-level plan identifier.
+ * --------
+ */
+void
+pgstat_report_plan_id(uint64 plan_id, bool force)
+{
+   volatile PgBackendStatus *beentry = MyBEEntry;
+
+   /*
+    * if track_activities is disabled, st_plan_id should already have been
+    * reset
+    */
+   if (!beentry || !pgstat_track_activities)
+       return;
+
+   /*
+    * We only report the top-level plan identifiers.  The stored plan_id is
+    * reset when a backend calls pgstat_report_activity(STATE_RUNNING), or
+    * with an explicit call to this function using the force flag.  If the
+    * saved plan identifier is not zero it means that it's not a top-level
+    * command, so ignore the one provided unless it's an explicit call to
+    * reset the identifier.
+    */
+   if (beentry->st_plan_id != 0 && !force)
+       return;
+
+   /*
+    * Update my status entry, following the protocol of bumping
+    * st_changecount before and after.  We use a volatile pointer here to
+    * ensure the compiler doesn't try to get cute.
+    */
+   PGSTAT_BEGIN_WRITE_ACTIVITY(beentry);
+   beentry->st_plan_id = plan_id;
+   PGSTAT_END_WRITE_ACTIVITY(beentry);
+}
 
 /* ----------
  * pgstat_report_appname() -
@@ -1106,6 +1149,21 @@ pgstat_get_my_query_id(void)
    return MyBEEntry->st_query_id;
 }
 
+/* ----------
+ * pgstat_get_my_plan_id() -
+ *
+ * Return current backend's plan identifier.
+ */
+uint64
+pgstat_get_my_plan_id(void)
+{
+   if (!MyBEEntry)
+       return 0;
+
+   /* No need for a lock, for roughly the same reasons as above. */
+   return MyBEEntry->st_plan_id;
+}
+
 /* ----------
  * pgstat_get_backend_type_by_proc_number() -
  *

diff --git a/src/include/nodes/plannodes.h b/src/include/nodes/plannodes.h
index f78bffd90cf8f76cc79f994464c8a752808418bb..658d76225e472b39b71234398b6cb755280408a1 100644 (file)
--- a/src/include/nodes/plannodes.h
+++ b/src/include/nodes/plannodes.h
@@ -55,6 +55,9 @@ typedef struct PlannedStmt
    /* query identifier (copied from Query) */
    uint64      queryId;
 
+   /* plan identifier (can be set by plugins) */
+   uint64      planId;
+
    /* is it insert|update|delete|merge RETURNING? */
    bool        hasReturning;
 

diff --git a/src/include/utils/backend_status.h b/src/include/utils/backend_status.h
index 1c9b4fe14d0628a6d8c653fb80c26bad47f945af..430ccd7d78e41e9083e3504368415cf65c717f02 100644 (file)
--- a/src/include/utils/backend_status.h
+++ b/src/include/utils/backend_status.h
@@ -171,6 +171,9 @@ typedef struct PgBackendStatus
 
    /* query identifier, optionally computed using post_parse_analyze_hook */
    uint64      st_query_id;
+
+   /* plan identifier, optionally computed using planner_hook */
+   uint64      st_plan_id;
 } PgBackendStatus;
 
 
@@ -319,6 +322,7 @@ extern void pgstat_clear_backend_activity_snapshot(void);
 /* Activity reporting functions */
 extern void pgstat_report_activity(BackendState state, const char *cmd_str);
 extern void pgstat_report_query_id(uint64 query_id, bool force);
+extern void pgstat_report_plan_id(uint64 plan_id, bool force);
 extern void pgstat_report_tempfile(size_t filesize);
 extern void pgstat_report_appname(const char *appname);
 extern void pgstat_report_xact_timestamp(TimestampTz tstamp);
@@ -326,6 +330,7 @@ extern const char *pgstat_get_backend_current_activity(int pid, bool checkUser);
 extern const char *pgstat_get_crashed_backend_activity(int pid, char *buffer,
                                                       int buflen);
 extern uint64 pgstat_get_my_query_id(void);
+extern uint64 pgstat_get_my_plan_id(void);
 extern BackendType pgstat_get_backend_type_by_proc_number(ProcNumber procNumber);