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david-rowleydavid-rowley
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Adjust tuplestore stats API
1eff827 added an API to tuplestore.c to allow callers to obtain storage telemetry data. That API wasn't quite good enough for callers that perform tuplestore_clear() as the telemetry functions only accounted for the current state of the tuplestore, not the maximums before tuplestore_clear() was called. There's a pending patch that would like to add tuplestore telemetry output to EXPLAIN ANALYZE for WindowAgg. That node type uses tuplestore_clear() before moving to the next window partition and we want to show the maximum space used, not the space used for the final partition. Reviewed-by: Tatsuo Ishii, Ashutosh Bapat Discussion: https://postgres/m/CAApHDvoY8cibGcicLV0fNh=9JVx9PANcWvhkdjBnDCc9Quqytg@mail.gmail.com
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+48
-38
lines changed

3 files changed

+48
-38
lines changed

‎src/backend/commands/explain.c‎

Lines changed: 9 additions & 8 deletions
Original file line numberDiff line numberDiff line change
@@ -3350,8 +3350,9 @@ static void
33503350
show_material_info(MaterialState *mstate, ExplainState *es)
33513351
{
33523352
Tuplestorestate *tupstore = mstate->tuplestorestate;
3353-
const char *storageType;
3354-
int64 spaceUsedKB;
3353+
char *maxStorageType;
3354+
int64 maxSpaceUsed,
3355+
maxSpaceUsedKB;
33553356

33563357
/*
33573358
* Nothing to show if ANALYZE option wasn't used or if execution didn't
@@ -3360,21 +3361,21 @@ show_material_info(MaterialState *mstate, ExplainState *es)
33603361
if (!es->analyze || tupstore == NULL)
33613362
return;
33623363

3363-
storageType = tuplestore_storage_type_name(tupstore);
3364-
spaceUsedKB = BYTES_TO_KILOBYTES(tuplestore_space_used(tupstore));
3364+
tuplestore_get_stats(tupstore, &maxStorageType, &maxSpaceUsed);
3365+
maxSpaceUsedKB = BYTES_TO_KILOBYTES(maxSpaceUsed);
33653366

33663367
if (es->format != EXPLAIN_FORMAT_TEXT)
33673368
{
3368-
ExplainPropertyText("Storage", storageType, es);
3369-
ExplainPropertyInteger("Maximum Storage", "kB", spaceUsedKB, es);
3369+
ExplainPropertyText("Storage", maxStorageType, es);
3370+
ExplainPropertyInteger("Maximum Storage", "kB", maxSpaceUsedKB, es);
33703371
}
33713372
else
33723373
{
33733374
ExplainIndentText(es);
33743375
appendStringInfo(es->str,
33753376
"Storage: %s Maximum Storage: " INT64_FORMAT "kB\n",
3376-
storageType,
3377-
spaceUsedKB);
3377+
maxStorageType,
3378+
maxSpaceUsedKB);
33783379
}
33793380
}
33803381

‎src/backend/utils/sort/tuplestore.c‎

Lines changed: 37 additions & 27 deletions
Original file line numberDiff line numberDiff line change
@@ -107,9 +107,10 @@ struct Tuplestorestate
107107
bool backward; /* store extra length words in file? */
108108
bool interXact; /* keep open through transactions? */
109109
bool truncated; /* tuplestore_trim has removed tuples? */
110+
bool usedDisk; /* used by tuplestore_get_stats() */
111+
int64 maxSpace; /* used by tuplestore_get_stats() */
110112
int64 availMem; /* remaining memory available, in bytes */
111113
int64 allowedMem; /* total memory allowed, in bytes */
112-
int64 maxSpace; /* maximum space used in memory */
113114
int64 tuples; /* number of tuples added */
114115
BufFile *myfile; /* underlying file, or NULL if none */
115116
MemoryContext context; /* memory context for holding tuples */
@@ -262,9 +263,10 @@ tuplestore_begin_common(int eflags, bool interXact, int maxKBytes)
262263
state->eflags = eflags;
263264
state->interXact = interXact;
264265
state->truncated = false;
266+
state->usedDisk = false;
267+
state->maxSpace = 0;
265268
state->allowedMem = maxKBytes * 1024L;
266269
state->availMem = state->allowedMem;
267-
state->maxSpace = 0;
268270
state->myfile = NULL;
269271

270272
/*
@@ -870,6 +872,14 @@ tuplestore_puttuple_common(Tuplestorestate *state, void *tuple)
870872
* though callers might drop the requirement.
871873
*/
872874
state->backward = (state->eflags & EXEC_FLAG_BACKWARD) != 0;
875+
876+
/*
877+
* Update the maximum space used before dumping the tuples. It's
878+
* possible that more space will be used by the tuples in memory
879+
* than the space that will be used on disk.
880+
*/
881+
tuplestore_updatemax(state);
882+
873883
state->status = TSS_WRITEFILE;
874884
dumptuples(state);
875885
break;
@@ -1444,7 +1454,7 @@ tuplestore_trim(Tuplestorestate *state)
14441454
Assert(nremove >= state->memtupdeleted);
14451455
Assert(nremove <= state->memtupcount);
14461456

1447-
/* before freeing any memory, update maxSpace */
1457+
/* before freeing any memory, update the statistics */
14481458
tuplestore_updatemax(state);
14491459

14501460
/* Release no-longer-needed tuples */
@@ -1491,45 +1501,46 @@ tuplestore_trim(Tuplestorestate *state)
14911501

14921502
/*
14931503
* tuplestore_updatemax
1494-
* Update maxSpace field
1504+
* Update the maximum space used by this tuplestore and the method used
1505+
* for storage.
14951506
*/
14961507
static void
14971508
tuplestore_updatemax(Tuplestorestate *state)
14981509
{
14991510
if (state->status == TSS_INMEM)
15001511
state->maxSpace = Max(state->maxSpace,
15011512
state->allowedMem - state->availMem);
1502-
}
1503-
1504-
/*
1505-
* tuplestore_storage_type_name
1506-
* Return a string description of the storage method used to store the
1507-
* tuples.
1508-
*/
1509-
const char *
1510-
tuplestore_storage_type_name(Tuplestorestate *state)
1511-
{
1512-
if (state->status == TSS_INMEM)
1513-
return "Memory";
15141513
else
1515-
return "Disk";
1514+
{
1515+
state->maxSpace = Max(state->maxSpace,
1516+
BufFileSize(state->myfile));
1517+
1518+
/*
1519+
* usedDisk never gets set to false again after spilling to disk, even
1520+
* if tuplestore_clear() is called and new tuples go to memory again.
1521+
*/
1522+
state->usedDisk = true;
1523+
}
15161524
}
15171525

15181526
/*
1519-
* tuplestore_space_used
1520-
* Return the maximum space used in memory unless the tuplestore has spilled
1521-
* to disk, in which case, return the disk space used.
1527+
* tuplestore_get_stats
1528+
* Obtain statistics about the maximum space used by the tuplestore.
1529+
* These statistics are the maximums and are not reset by calls to
1530+
* tuplestore_trim() or tuplestore_clear().
15221531
*/
1523-
int64
1524-
tuplestore_space_used(Tuplestorestate *state)
1532+
void
1533+
tuplestore_get_stats(Tuplestorestate *state, char **max_storage_type,
1534+
int64 *max_space)
15251535
{
1526-
/* First, update the maxSpace field */
15271536
tuplestore_updatemax(state);
15281537

1529-
if (state->status == TSS_INMEM)
1530-
return state->maxSpace;
1538+
if (state->usedDisk)
1539+
*max_storage_type = "Disk";
15311540
else
1532-
return BufFileSize(state->myfile);
1541+
*max_storage_type = "Memory";
1542+
1543+
*max_space = state->maxSpace;
15331544
}
15341545

15351546
/*
@@ -1601,7 +1612,6 @@ writetup_heap(Tuplestorestate *state, void *tup)
16011612
if (state->backward) /* need trailing length word? */
16021613
BufFileWrite(state->myfile, &tuplen, sizeof(tuplen));
16031614

1604-
/* no need to call tuplestore_updatemax() when not in TSS_INMEM */
16051615
FREEMEM(state, GetMemoryChunkSpace(tuple));
16061616
heap_free_minimal_tuple(tuple);
16071617
}

‎src/include/utils/tuplestore.h‎

Lines changed: 2 additions & 3 deletions
Original file line numberDiff line numberDiff line change
@@ -65,9 +65,8 @@ extern void tuplestore_copy_read_pointer(Tuplestorestate *state,
6565

6666
extern void tuplestore_trim(Tuplestorestate *state);
6767

68-
extern const char *tuplestore_storage_type_name(Tuplestorestate *state);
69-
70-
extern int64 tuplestore_space_used(Tuplestorestate *state);
68+
extern void tuplestore_get_stats(Tuplestorestate *state, char **storage_type,
69+
int64 *max_space);
7170

7271
extern bool tuplestore_in_memory(Tuplestorestate *state);
7372

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