From 439f76c208fd38e98fb742990dd445af483b5010 Mon Sep 17 00:00:00 2001 From: Robert Haas Date: Wed, 5 Mar 2025 16:06:07 -0500 Subject: [PATCH v4 2/3] Add some new hooks so extensions can add details to EXPLAIN. Specifically, add a per-node hook that is called after the per-node information has been displayed but before we display children, and a per-query hook that is called after existing query-level information is printed. This assumes that extension-added information should always go at the end rather than the beginning or the middle, but that seems like an acceptable limitation for simplicity. It also assumes that extensions will only want to add information, not remove or reformat existing details; those also seem like acceptable restrictions, at least for now. If multiple EXPLAIN extensions are used, the order in which any additional details are printed is likely to depend on the order in which the modules are loaded. That doesn't seem great; so possibly we should add some kind of registration interface that also allows extensions to specify a priority, so that we can print details in a predictable order. However, that would be less similar to existing hooks, and perhaps not worth the complexity, so do this for now. --- src/backend/commands/explain.c | 13 +++++++++++++ src/include/commands/explain.h | 17 +++++++++++++++++ 2 files changed, 30 insertions(+) diff --git a/src/backend/commands/explain.c b/src/backend/commands/explain.c index 7c203420fed..a3d40c9934f 100644 --- a/src/backend/commands/explain.c +++ b/src/backend/commands/explain.c @@ -51,6 +51,9 @@ ExplainOneQuery_hook_type ExplainOneQuery_hook = NULL; /* Hook for plugins to get control in explain_get_index_name() */ explain_get_index_name_hook_type explain_get_index_name_hook = NULL; +/* per-plan and per-node hooks for plugins to print additional info */ +explain_per_plan_hook_type explain_per_plan_hook = NULL; +explain_per_node_hook_type explain_per_node_hook = NULL; /* * Various places within need to convert bytes to kilobytes. Round these up @@ -647,6 +650,11 @@ ExplainOnePlan(PlannedStmt *plannedstmt, CachedPlan *cplan, if (es->serialize != EXPLAIN_SERIALIZE_NONE) ExplainPrintSerialize(es, &serializeMetrics); + /* Allow plugins to print additional information */ + if (explain_per_plan_hook) + (*explain_per_plan_hook) (plannedstmt, into, es, queryString, + params, queryEnv); + /* * Close down the query and free resources. Include time for this in the * total execution time (although it should be pretty minimal). @@ -2307,6 +2315,11 @@ ExplainNode(PlanState *planstate, List *ancestors, ExplainFlushWorkersState(es); es->workers_state = save_workers_state; + /* Allow plugins to print additional information */ + if (explain_per_node_hook) + (*explain_per_node_hook) (planstate, ancestors, relationship, + plan_name, es); + /* * If partition pruning was done during executor initialization, the * number of child plans we'll display below will be less than the number diff --git a/src/include/commands/explain.h b/src/include/commands/explain.h index 0ea313475f6..3ba7d16239f 100644 --- a/src/include/commands/explain.h +++ b/src/include/commands/explain.h @@ -28,6 +28,23 @@ typedef void (*ExplainOneQuery_hook_type) (Query *query, QueryEnvironment *queryEnv); extern PGDLLIMPORT ExplainOneQuery_hook_type ExplainOneQuery_hook; +/* Hook for EXPLAIN plugins to print extra information for each plan */ +typedef void (*explain_per_plan_hook_type) (PlannedStmt *plannedstmt, + IntoClause *into, + ExplainState *es, + const char *queryString, + ParamListInfo params, + QueryEnvironment *queryEnv); +extern PGDLLIMPORT explain_per_plan_hook_type explain_per_plan_hook; + +/* Hook for EXPLAIN plugins to print extra fields on individual plan nodes */ +typedef void (*explain_per_node_hook_type) (PlanState *planstate, + List *ancestors, + const char *relationship, + const char *plan_name, + ExplainState *es); +extern PGDLLIMPORT explain_per_node_hook_type explain_per_node_hook; + /* Hook for plugins to get control in explain_get_index_name() */ typedef const char *(*explain_get_index_name_hook_type) (Oid indexId); extern PGDLLIMPORT explain_get_index_name_hook_type explain_get_index_name_hook; -- 2.39.3 (Apple Git-145)