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| 1 | +/*------------------------------------------------------------------------- |
| 2 | + * |
| 3 | + * auto_explain.c |
| 4 | + * |
| 5 | + * |
| 6 | + * Copyright (c) 2008, PostgreSQL Global Development Group |
| 7 | + * |
| 8 | + * IDENTIFICATION |
| 9 | + * $PostgreSQL: pgsql/contrib/auto_explain/auto_explain.c,v 1.1 2008/11/19 02:59:28 tgl Exp $ |
| 10 | + * |
| 11 | + *------------------------------------------------------------------------- |
| 12 | + */ |
| 13 | +#include "postgres.h" |
| 14 | + |
| 15 | +#include "commands/explain.h" |
| 16 | +#include "executor/instrument.h" |
| 17 | +#include "utils/guc.h" |
| 18 | + |
| 19 | +PG_MODULE_MAGIC; |
| 20 | + |
| 21 | +#define GUCNAME(name) ("explain." name) |
| 22 | + |
| 23 | +/* GUC variables */ |
| 24 | +static int explain_log_min_duration = -1; /* msec or -1 */ |
| 25 | +static bool explain_log_analyze = false; |
| 26 | +static bool explain_log_verbose = false; |
| 27 | +static bool explain_log_nested = false; |
| 28 | + |
| 29 | +/* Current nesting depth of ExecutorRun calls */ |
| 30 | +static int nesting_level = 0; |
| 31 | + |
| 32 | +/* Saved hook values in case of unload */ |
| 33 | +static ExecutorStart_hook_type prev_ExecutorStart = NULL; |
| 34 | +static ExecutorRun_hook_type prev_ExecutorRun = NULL; |
| 35 | +static ExecutorEnd_hook_type prev_ExecutorEnd = NULL; |
| 36 | + |
| 37 | +#define auto_explain_enabled() \ |
| 38 | + (explain_log_min_duration >= 0 && \ |
| 39 | + (nesting_level == 0 || explain_log_nested)) |
| 40 | + |
| 41 | +void _PG_init(void); |
| 42 | +void _PG_fini(void); |
| 43 | + |
| 44 | +static void explain_ExecutorStart(QueryDesc *queryDesc, int eflags); |
| 45 | +static void explain_ExecutorRun(QueryDesc *queryDesc, |
| 46 | + ScanDirection direction, |
| 47 | + long count); |
| 48 | +static void explain_ExecutorEnd(QueryDesc *queryDesc); |
| 49 | + |
| 50 | + |
| 51 | +/* |
| 52 | + * Module load callback |
| 53 | + */ |
| 54 | +void |
| 55 | +_PG_init(void) |
| 56 | +{ |
| 57 | + /* Define custom GUC variables. */ |
| 58 | + DefineCustomIntVariable(GUCNAME("log_min_duration"), |
| 59 | + "Sets the minimum execution time above which plans will be logged.", |
| 60 | + "Zero prints all plans. -1 turns this feature off.", |
| 61 | + &explain_log_min_duration, |
| 62 | + -1, |
| 63 | + -1, INT_MAX / 1000, |
| 64 | + PGC_SUSET, |
| 65 | + GUC_UNIT_MS, |
| 66 | + NULL, |
| 67 | + NULL); |
| 68 | + |
| 69 | + DefineCustomBoolVariable(GUCNAME("log_analyze"), |
| 70 | + "Use EXPLAIN ANALYZE for plan logging.", |
| 71 | + NULL, |
| 72 | + &explain_log_analyze, |
| 73 | + false, |
| 74 | + PGC_SUSET, |
| 75 | + 0, |
| 76 | + NULL, |
| 77 | + NULL); |
| 78 | + |
| 79 | + DefineCustomBoolVariable(GUCNAME("log_verbose"), |
| 80 | + "Use EXPLAIN VERBOSE for plan logging.", |
| 81 | + NULL, |
| 82 | + &explain_log_verbose, |
| 83 | + false, |
| 84 | + PGC_SUSET, |
| 85 | + 0, |
| 86 | + NULL, |
| 87 | + NULL); |
| 88 | + |
| 89 | + DefineCustomBoolVariable(GUCNAME("log_nested_statements"), |
| 90 | + "Log nested statements.", |
| 91 | + NULL, |
| 92 | + &explain_log_nested, |
| 93 | + false, |
| 94 | + PGC_SUSET, |
| 95 | + 0, |
| 96 | + NULL, |
| 97 | + NULL); |
| 98 | + |
| 99 | + /* Install hooks. */ |
| 100 | + prev_ExecutorStart = ExecutorStart_hook; |
| 101 | + ExecutorStart_hook = explain_ExecutorStart; |
| 102 | + prev_ExecutorRun = ExecutorRun_hook; |
| 103 | + ExecutorRun_hook = explain_ExecutorRun; |
| 104 | + prev_ExecutorEnd = ExecutorEnd_hook; |
| 105 | + ExecutorEnd_hook = explain_ExecutorEnd; |
| 106 | +} |
| 107 | + |
| 108 | +/* |
| 109 | + * Module unload callback |
| 110 | + */ |
| 111 | +void |
| 112 | +_PG_fini(void) |
| 113 | +{ |
| 114 | + /* Uninstall hooks. */ |
| 115 | + ExecutorStart_hook = prev_ExecutorStart; |
| 116 | + ExecutorRun_hook = prev_ExecutorRun; |
| 117 | + ExecutorEnd_hook = prev_ExecutorEnd; |
| 118 | +} |
| 119 | + |
| 120 | +/* |
| 121 | + * ExecutorStart hook: start up logging if needed |
| 122 | + */ |
| 123 | +void |
| 124 | +explain_ExecutorStart(QueryDesc *queryDesc, int eflags) |
| 125 | +{ |
| 126 | + if (auto_explain_enabled()) |
| 127 | + { |
| 128 | + /* Enable per-node instrumentation iff log_analyze is required. */ |
| 129 | + if (explain_log_analyze && (eflags & EXEC_FLAG_EXPLAIN_ONLY) == 0) |
| 130 | + queryDesc->doInstrument = true; |
| 131 | + } |
| 132 | + |
| 133 | + if (prev_ExecutorStart) |
| 134 | + prev_ExecutorStart(queryDesc, eflags); |
| 135 | + else |
| 136 | + standard_ExecutorStart(queryDesc, eflags); |
| 137 | + |
| 138 | + if (auto_explain_enabled()) |
| 139 | + { |
| 140 | + /* |
| 141 | + * Set up to track total elapsed time in ExecutorRun. Make sure |
| 142 | + * the space is allocated in the per-query context so it will go |
| 143 | + * away at ExecutorEnd. |
| 144 | + */ |
| 145 | + if (queryDesc->totaltime == NULL) |
| 146 | + { |
| 147 | + MemoryContext oldcxt; |
| 148 | + |
| 149 | + oldcxt = MemoryContextSwitchTo(queryDesc->estate->es_query_cxt); |
| 150 | + queryDesc->totaltime = InstrAlloc(1); |
| 151 | + MemoryContextSwitchTo(oldcxt); |
| 152 | + } |
| 153 | + } |
| 154 | +} |
| 155 | + |
| 156 | +/* |
| 157 | + * ExecutorRun hook: all we need do is track nesting depth |
| 158 | + */ |
| 159 | +void |
| 160 | +explain_ExecutorRun(QueryDesc *queryDesc, ScanDirection direction, long count) |
| 161 | +{ |
| 162 | + nesting_level++; |
| 163 | + PG_TRY(); |
| 164 | + { |
| 165 | + if (prev_ExecutorRun) |
| 166 | + prev_ExecutorRun(queryDesc, direction, count); |
| 167 | + else |
| 168 | + standard_ExecutorRun(queryDesc, direction, count); |
| 169 | + nesting_level--; |
| 170 | + } |
| 171 | + PG_CATCH(); |
| 172 | + { |
| 173 | + nesting_level--; |
| 174 | + PG_RE_THROW(); |
| 175 | + } |
| 176 | + PG_END_TRY(); |
| 177 | +} |
| 178 | + |
| 179 | +/* |
| 180 | + * ExecutorEnd hook: log results if needed |
| 181 | + */ |
| 182 | +void |
| 183 | +explain_ExecutorEnd(QueryDesc *queryDesc) |
| 184 | +{ |
| 185 | + if (queryDesc->totaltime && auto_explain_enabled()) |
| 186 | + { |
| 187 | + double msec; |
| 188 | + |
| 189 | + /* |
| 190 | + * Make sure stats accumulation is done. (Note: it's okay if |
| 191 | + * several levels of hook all do this.) |
| 192 | + */ |
| 193 | + InstrEndLoop(queryDesc->totaltime); |
| 194 | + |
| 195 | + /* Log plan if duration is exceeded. */ |
| 196 | + msec = queryDesc->totaltime->total * 1000.0; |
| 197 | + if (msec >= explain_log_min_duration) |
| 198 | + { |
| 199 | + StringInfoData buf; |
| 200 | + |
| 201 | + initStringInfo(&buf); |
| 202 | + ExplainPrintPlan(&buf, queryDesc, |
| 203 | + queryDesc->doInstrument && explain_log_analyze, |
| 204 | + explain_log_verbose); |
| 205 | + |
| 206 | + /* Remove last line break */ |
| 207 | + if (buf.len > 0 && buf.data[buf.len - 1] == '\n') |
| 208 | + buf.data[--buf.len] = '\0'; |
| 209 | + |
| 210 | + /* |
| 211 | + * Note: we rely on the existing logging of context or |
| 212 | + * debug_query_string to identify just which statement is being |
| 213 | + * reported. This isn't ideal but trying to do it here would |
| 214 | + * often result in duplication. |
| 215 | + */ |
| 216 | + ereport(LOG, |
| 217 | + (errmsg("duration: %.3f ms plan:\n%s", |
| 218 | + msec, buf.data))); |
| 219 | + |
| 220 | + pfree(buf.data); |
| 221 | + } |
| 222 | + } |
| 223 | + |
| 224 | + if (prev_ExecutorEnd) |
| 225 | + prev_ExecutorEnd(queryDesc); |
| 226 | + else |
| 227 | + standard_ExecutorEnd(queryDesc); |
| 228 | +} |
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