LCOV - code coverage report
Current view: top level - contrib/auto_explain - auto_explain.c (source / functions) Hit Total Coverage
Test: PostgreSQL 17devel Lines: 92 103 89.3 %
Date: 2024-04-25 01:13:18 Functions: 6 6 100.0 %
Legend: Lines: hit not hit

          Line data    Source code
       1             : /*-------------------------------------------------------------------------
       2             :  *
       3             :  * auto_explain.c
       4             :  *
       5             :  *
       6             :  * Copyright (c) 2008-2024, PostgreSQL Global Development Group
       7             :  *
       8             :  * IDENTIFICATION
       9             :  *    contrib/auto_explain/auto_explain.c
      10             :  *
      11             :  *-------------------------------------------------------------------------
      12             :  */
      13             : #include "postgres.h"
      14             : 
      15             : #include <limits.h>
      16             : 
      17             : #include "access/parallel.h"
      18             : #include "commands/explain.h"
      19             : #include "common/pg_prng.h"
      20             : #include "executor/instrument.h"
      21             : #include "jit/jit.h"
      22             : #include "nodes/params.h"
      23             : #include "utils/guc.h"
      24             : 
      25          22 : PG_MODULE_MAGIC;
      26             : 
      27             : /* GUC variables */
      28             : static int  auto_explain_log_min_duration = -1; /* msec or -1 */
      29             : static int  auto_explain_log_parameter_max_length = -1; /* bytes or -1 */
      30             : static bool auto_explain_log_analyze = false;
      31             : static bool auto_explain_log_verbose = false;
      32             : static bool auto_explain_log_buffers = false;
      33             : static bool auto_explain_log_wal = false;
      34             : static bool auto_explain_log_triggers = false;
      35             : static bool auto_explain_log_timing = true;
      36             : static bool auto_explain_log_settings = false;
      37             : static int  auto_explain_log_format = EXPLAIN_FORMAT_TEXT;
      38             : static int  auto_explain_log_level = LOG;
      39             : static bool auto_explain_log_nested_statements = false;
      40             : static double auto_explain_sample_rate = 1;
      41             : 
      42             : static const struct config_enum_entry format_options[] = {
      43             :     {"text", EXPLAIN_FORMAT_TEXT, false},
      44             :     {"xml", EXPLAIN_FORMAT_XML, false},
      45             :     {"json", EXPLAIN_FORMAT_JSON, false},
      46             :     {"yaml", EXPLAIN_FORMAT_YAML, false},
      47             :     {NULL, 0, false}
      48             : };
      49             : 
      50             : static const struct config_enum_entry loglevel_options[] = {
      51             :     {"debug5", DEBUG5, false},
      52             :     {"debug4", DEBUG4, false},
      53             :     {"debug3", DEBUG3, false},
      54             :     {"debug2", DEBUG2, false},
      55             :     {"debug1", DEBUG1, false},
      56             :     {"debug", DEBUG2, true},
      57             :     {"info", INFO, false},
      58             :     {"notice", NOTICE, false},
      59             :     {"warning", WARNING, false},
      60             :     {"log", LOG, false},
      61             :     {NULL, 0, false}
      62             : };
      63             : 
      64             : /* Current nesting depth of ExecutorRun calls */
      65             : static int  nesting_level = 0;
      66             : 
      67             : /* Is the current top-level query to be sampled? */
      68             : static bool current_query_sampled = false;
      69             : 
      70             : #define auto_explain_enabled() \
      71             :     (auto_explain_log_min_duration >= 0 && \
      72             :      (nesting_level == 0 || auto_explain_log_nested_statements) && \
      73             :      current_query_sampled)
      74             : 
      75             : /* Saved hook values in case of unload */
      76             : static ExecutorStart_hook_type prev_ExecutorStart = NULL;
      77             : static ExecutorRun_hook_type prev_ExecutorRun = NULL;
      78             : static ExecutorFinish_hook_type prev_ExecutorFinish = NULL;
      79             : static ExecutorEnd_hook_type prev_ExecutorEnd = NULL;
      80             : 
      81             : static void explain_ExecutorStart(QueryDesc *queryDesc, int eflags);
      82             : static void explain_ExecutorRun(QueryDesc *queryDesc,
      83             :                                 ScanDirection direction,
      84             :                                 uint64 count, bool execute_once);
      85             : static void explain_ExecutorFinish(QueryDesc *queryDesc);
      86             : static void explain_ExecutorEnd(QueryDesc *queryDesc);
      87             : 
      88             : 
      89             : /*
      90             :  * Module load callback
      91             :  */
      92             : void
      93          22 : _PG_init(void)
      94             : {
      95             :     /* Define custom GUC variables. */
      96          22 :     DefineCustomIntVariable("auto_explain.log_min_duration",
      97             :                             "Sets the minimum execution time above which plans will be logged.",
      98             :                             "Zero prints all plans. -1 turns this feature off.",
      99             :                             &auto_explain_log_min_duration,
     100             :                             -1,
     101             :                             -1, INT_MAX,
     102             :                             PGC_SUSET,
     103             :                             GUC_UNIT_MS,
     104             :                             NULL,
     105             :                             NULL,
     106             :                             NULL);
     107             : 
     108          22 :     DefineCustomIntVariable("auto_explain.log_parameter_max_length",
     109             :                             "Sets the maximum length of query parameters to log.",
     110             :                             "Zero logs no query parameters, -1 logs them in full.",
     111             :                             &auto_explain_log_parameter_max_length,
     112             :                             -1,
     113             :                             -1, INT_MAX,
     114             :                             PGC_SUSET,
     115             :                             GUC_UNIT_BYTE,
     116             :                             NULL,
     117             :                             NULL,
     118             :                             NULL);
     119             : 
     120          22 :     DefineCustomBoolVariable("auto_explain.log_analyze",
     121             :                              "Use EXPLAIN ANALYZE for plan logging.",
     122             :                              NULL,
     123             :                              &auto_explain_log_analyze,
     124             :                              false,
     125             :                              PGC_SUSET,
     126             :                              0,
     127             :                              NULL,
     128             :                              NULL,
     129             :                              NULL);
     130             : 
     131          22 :     DefineCustomBoolVariable("auto_explain.log_settings",
     132             :                              "Log modified configuration parameters affecting query planning.",
     133             :                              NULL,
     134             :                              &auto_explain_log_settings,
     135             :                              false,
     136             :                              PGC_SUSET,
     137             :                              0,
     138             :                              NULL,
     139             :                              NULL,
     140             :                              NULL);
     141             : 
     142          22 :     DefineCustomBoolVariable("auto_explain.log_verbose",
     143             :                              "Use EXPLAIN VERBOSE for plan logging.",
     144             :                              NULL,
     145             :                              &auto_explain_log_verbose,
     146             :                              false,
     147             :                              PGC_SUSET,
     148             :                              0,
     149             :                              NULL,
     150             :                              NULL,
     151             :                              NULL);
     152             : 
     153          22 :     DefineCustomBoolVariable("auto_explain.log_buffers",
     154             :                              "Log buffers usage.",
     155             :                              NULL,
     156             :                              &auto_explain_log_buffers,
     157             :                              false,
     158             :                              PGC_SUSET,
     159             :                              0,
     160             :                              NULL,
     161             :                              NULL,
     162             :                              NULL);
     163             : 
     164          22 :     DefineCustomBoolVariable("auto_explain.log_wal",
     165             :                              "Log WAL usage.",
     166             :                              NULL,
     167             :                              &auto_explain_log_wal,
     168             :                              false,
     169             :                              PGC_SUSET,
     170             :                              0,
     171             :                              NULL,
     172             :                              NULL,
     173             :                              NULL);
     174             : 
     175          22 :     DefineCustomBoolVariable("auto_explain.log_triggers",
     176             :                              "Include trigger statistics in plans.",
     177             :                              "This has no effect unless log_analyze is also set.",
     178             :                              &auto_explain_log_triggers,
     179             :                              false,
     180             :                              PGC_SUSET,
     181             :                              0,
     182             :                              NULL,
     183             :                              NULL,
     184             :                              NULL);
     185             : 
     186          22 :     DefineCustomEnumVariable("auto_explain.log_format",
     187             :                              "EXPLAIN format to be used for plan logging.",
     188             :                              NULL,
     189             :                              &auto_explain_log_format,
     190             :                              EXPLAIN_FORMAT_TEXT,
     191             :                              format_options,
     192             :                              PGC_SUSET,
     193             :                              0,
     194             :                              NULL,
     195             :                              NULL,
     196             :                              NULL);
     197             : 
     198          22 :     DefineCustomEnumVariable("auto_explain.log_level",
     199             :                              "Log level for the plan.",
     200             :                              NULL,
     201             :                              &auto_explain_log_level,
     202             :                              LOG,
     203             :                              loglevel_options,
     204             :                              PGC_SUSET,
     205             :                              0,
     206             :                              NULL,
     207             :                              NULL,
     208             :                              NULL);
     209             : 
     210          22 :     DefineCustomBoolVariable("auto_explain.log_nested_statements",
     211             :                              "Log nested statements.",
     212             :                              NULL,
     213             :                              &auto_explain_log_nested_statements,
     214             :                              false,
     215             :                              PGC_SUSET,
     216             :                              0,
     217             :                              NULL,
     218             :                              NULL,
     219             :                              NULL);
     220             : 
     221          22 :     DefineCustomBoolVariable("auto_explain.log_timing",
     222             :                              "Collect timing data, not just row counts.",
     223             :                              NULL,
     224             :                              &auto_explain_log_timing,
     225             :                              true,
     226             :                              PGC_SUSET,
     227             :                              0,
     228             :                              NULL,
     229             :                              NULL,
     230             :                              NULL);
     231             : 
     232          22 :     DefineCustomRealVariable("auto_explain.sample_rate",
     233             :                              "Fraction of queries to process.",
     234             :                              NULL,
     235             :                              &auto_explain_sample_rate,
     236             :                              1.0,
     237             :                              0.0,
     238             :                              1.0,
     239             :                              PGC_SUSET,
     240             :                              0,
     241             :                              NULL,
     242             :                              NULL,
     243             :                              NULL);
     244             : 
     245          22 :     MarkGUCPrefixReserved("auto_explain");
     246             : 
     247             :     /* Install hooks. */
     248          22 :     prev_ExecutorStart = ExecutorStart_hook;
     249          22 :     ExecutorStart_hook = explain_ExecutorStart;
     250          22 :     prev_ExecutorRun = ExecutorRun_hook;
     251          22 :     ExecutorRun_hook = explain_ExecutorRun;
     252          22 :     prev_ExecutorFinish = ExecutorFinish_hook;
     253          22 :     ExecutorFinish_hook = explain_ExecutorFinish;
     254          22 :     prev_ExecutorEnd = ExecutorEnd_hook;
     255          22 :     ExecutorEnd_hook = explain_ExecutorEnd;
     256          22 : }
     257             : 
     258             : /*
     259             :  * ExecutorStart hook: start up logging if needed
     260             :  */
     261             : static void
     262          20 : explain_ExecutorStart(QueryDesc *queryDesc, int eflags)
     263             : {
     264             :     /*
     265             :      * At the beginning of each top-level statement, decide whether we'll
     266             :      * sample this statement.  If nested-statement explaining is enabled,
     267             :      * either all nested statements will be explained or none will.
     268             :      *
     269             :      * When in a parallel worker, we should do nothing, which we can implement
     270             :      * cheaply by pretending we decided not to sample the current statement.
     271             :      * If EXPLAIN is active in the parent session, data will be collected and
     272             :      * reported back to the parent, and it's no business of ours to interfere.
     273             :      */
     274          20 :     if (nesting_level == 0)
     275             :     {
     276          20 :         if (auto_explain_log_min_duration >= 0 && !IsParallelWorker())
     277          20 :             current_query_sampled = (pg_prng_double(&pg_global_prng_state) < auto_explain_sample_rate);
     278             :         else
     279           0 :             current_query_sampled = false;
     280             :     }
     281             : 
     282          20 :     if (auto_explain_enabled())
     283             :     {
     284             :         /* Enable per-node instrumentation iff log_analyze is required. */
     285          20 :         if (auto_explain_log_analyze && (eflags & EXEC_FLAG_EXPLAIN_ONLY) == 0)
     286             :         {
     287          20 :             if (auto_explain_log_timing)
     288          20 :                 queryDesc->instrument_options |= INSTRUMENT_TIMER;
     289             :             else
     290           0 :                 queryDesc->instrument_options |= INSTRUMENT_ROWS;
     291          20 :             if (auto_explain_log_buffers)
     292           0 :                 queryDesc->instrument_options |= INSTRUMENT_BUFFERS;
     293          20 :             if (auto_explain_log_wal)
     294           0 :                 queryDesc->instrument_options |= INSTRUMENT_WAL;
     295             :         }
     296             :     }
     297             : 
     298          20 :     if (prev_ExecutorStart)
     299           0 :         prev_ExecutorStart(queryDesc, eflags);
     300             :     else
     301          20 :         standard_ExecutorStart(queryDesc, eflags);
     302             : 
     303          20 :     if (auto_explain_enabled())
     304             :     {
     305             :         /*
     306             :          * Set up to track total elapsed time in ExecutorRun.  Make sure the
     307             :          * space is allocated in the per-query context so it will go away at
     308             :          * ExecutorEnd.
     309             :          */
     310          20 :         if (queryDesc->totaltime == NULL)
     311             :         {
     312             :             MemoryContext oldcxt;
     313             : 
     314          20 :             oldcxt = MemoryContextSwitchTo(queryDesc->estate->es_query_cxt);
     315          20 :             queryDesc->totaltime = InstrAlloc(1, INSTRUMENT_ALL, false);
     316          20 :             MemoryContextSwitchTo(oldcxt);
     317             :         }
     318             :     }
     319          20 : }
     320             : 
     321             : /*
     322             :  * ExecutorRun hook: all we need do is track nesting depth
     323             :  */
     324             : static void
     325          20 : explain_ExecutorRun(QueryDesc *queryDesc, ScanDirection direction,
     326             :                     uint64 count, bool execute_once)
     327             : {
     328          20 :     nesting_level++;
     329          20 :     PG_TRY();
     330             :     {
     331          20 :         if (prev_ExecutorRun)
     332           0 :             prev_ExecutorRun(queryDesc, direction, count, execute_once);
     333             :         else
     334          20 :             standard_ExecutorRun(queryDesc, direction, count, execute_once);
     335             :     }
     336           0 :     PG_FINALLY();
     337             :     {
     338          20 :         nesting_level--;
     339             :     }
     340          20 :     PG_END_TRY();
     341          20 : }
     342             : 
     343             : /*
     344             :  * ExecutorFinish hook: all we need do is track nesting depth
     345             :  */
     346             : static void
     347          20 : explain_ExecutorFinish(QueryDesc *queryDesc)
     348             : {
     349          20 :     nesting_level++;
     350          20 :     PG_TRY();
     351             :     {
     352          20 :         if (prev_ExecutorFinish)
     353           0 :             prev_ExecutorFinish(queryDesc);
     354             :         else
     355          20 :             standard_ExecutorFinish(queryDesc);
     356             :     }
     357           0 :     PG_FINALLY();
     358             :     {
     359          20 :         nesting_level--;
     360             :     }
     361          20 :     PG_END_TRY();
     362          20 : }
     363             : 
     364             : /*
     365             :  * ExecutorEnd hook: log results if needed
     366             :  */
     367             : static void
     368          20 : explain_ExecutorEnd(QueryDesc *queryDesc)
     369             : {
     370          20 :     if (queryDesc->totaltime && auto_explain_enabled())
     371             :     {
     372             :         MemoryContext oldcxt;
     373             :         double      msec;
     374             : 
     375             :         /*
     376             :          * Make sure we operate in the per-query context, so any cruft will be
     377             :          * discarded later during ExecutorEnd.
     378             :          */
     379          20 :         oldcxt = MemoryContextSwitchTo(queryDesc->estate->es_query_cxt);
     380             : 
     381             :         /*
     382             :          * Make sure stats accumulation is done.  (Note: it's okay if several
     383             :          * levels of hook all do this.)
     384             :          */
     385          20 :         InstrEndLoop(queryDesc->totaltime);
     386             : 
     387             :         /* Log plan if duration is exceeded. */
     388          20 :         msec = queryDesc->totaltime->total * 1000.0;
     389          20 :         if (msec >= auto_explain_log_min_duration)
     390             :         {
     391          20 :             ExplainState *es = NewExplainState();
     392             : 
     393          20 :             es->analyze = (queryDesc->instrument_options && auto_explain_log_analyze);
     394          20 :             es->verbose = auto_explain_log_verbose;
     395          20 :             es->buffers = (es->analyze && auto_explain_log_buffers);
     396          20 :             es->wal = (es->analyze && auto_explain_log_wal);
     397          20 :             es->timing = (es->analyze && auto_explain_log_timing);
     398          20 :             es->summary = es->analyze;
     399             :             /* No support for MEMORY */
     400             :             /* es->memory = false; */
     401          20 :             es->format = auto_explain_log_format;
     402          20 :             es->settings = auto_explain_log_settings;
     403             : 
     404          20 :             ExplainBeginOutput(es);
     405          20 :             ExplainQueryText(es, queryDesc);
     406          20 :             ExplainQueryParameters(es, queryDesc->params, auto_explain_log_parameter_max_length);
     407          20 :             ExplainPrintPlan(es, queryDesc);
     408          20 :             if (es->analyze && auto_explain_log_triggers)
     409           0 :                 ExplainPrintTriggers(es, queryDesc);
     410          20 :             if (es->costs)
     411          20 :                 ExplainPrintJITSummary(es, queryDesc);
     412          20 :             ExplainEndOutput(es);
     413             : 
     414             :             /* Remove last line break */
     415          20 :             if (es->str->len > 0 && es->str->data[es->str->len - 1] == '\n')
     416          14 :                 es->str->data[--es->str->len] = '\0';
     417             : 
     418             :             /* Fix JSON to output an object */
     419          20 :             if (auto_explain_log_format == EXPLAIN_FORMAT_JSON)
     420             :             {
     421           6 :                 es->str->data[0] = '{';
     422           6 :                 es->str->data[es->str->len - 1] = '}';
     423             :             }
     424             : 
     425             :             /*
     426             :              * Note: we rely on the existing logging of context or
     427             :              * debug_query_string to identify just which statement is being
     428             :              * reported.  This isn't ideal but trying to do it here would
     429             :              * often result in duplication.
     430             :              */
     431          20 :             ereport(auto_explain_log_level,
     432             :                     (errmsg("duration: %.3f ms  plan:\n%s",
     433             :                             msec, es->str->data),
     434             :                      errhidestmt(true)));
     435             :         }
     436             : 
     437          20 :         MemoryContextSwitchTo(oldcxt);
     438             :     }
     439             : 
     440          20 :     if (prev_ExecutorEnd)
     441           0 :         prev_ExecutorEnd(queryDesc);
     442             :     else
     443          20 :         standard_ExecutorEnd(queryDesc);
     444          20 : }

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