Maciek Sakrejda <m.sakre...@gmail.com> writes:
> Okay. Does not getting as many workers as it asks for include
> sometimes getting zero, completely changing the actual output?
Yup :-(. We could possibly avoid that by running the explain
test by itself rather than in a parallel group, but I don't
especially want to add yet more non-parallelizable tests.
Meanwhile, I spent some time looking at the code, and wasn't very happy
with it. I'm on board with the general plan of redirecting EXPLAIN
output into per-worker buffers that we eventually recombine, but I think
that this particular coding is pretty unmaintainable/unextensible.
In particular, I'm really unhappy that the code is ignoring EXPLAIN's
grouping_state stack. That means that when it's formatting fields that
belong to the per-worker group, it's using the state-stack entry that
corresponds to the plan node's main level. This seems to accidentally
work, but that fact depends on a number of shaky assumptions:
* Before messing with any per-worker data, we've always emitted at
least one field in the plan node's main level, so that the state-stack
entry isn't at its initial state for the level.
* Before actually emitting the shunted-aside data, we've always emitted
a "Worker Number" field in correct format within the per-worker group,
so that the formatting state is now correct for a non-initial field.
* There is no formatting difference between any non-first fields in
a level (ie the state stack entries are basically just booleans),
so that it doesn't matter how many plan-node fields we emitted before
starting the per-worker data, so long as there was at least one, nor
does transiently abusing the plan node level's stack entry like this
break the formatting of subsequent plan-node-level fields.
Now maybe we'll never implement an output format that breaks that
last assumption, and maybe we'll never rearrange the EXPLAIN code
in a way that breaks either of the first two. But I don't like those
assumptions too much. I also didn't like the code's assumption that
all the non-text formats interpret es->indent the same.
I also noted an actual bug, which is that the patch fails regression
testing under force_parallel_mode = regress. This isn't really your
fault, because the issue is in this obscure and poorly-commented hack
in show_sort_info:
* You might think we should just skip this stanza entirely when
* es->hide_workers is true, but then we'd get no sort-method output at
* all. We have to make it look like worker 0's data is top-level data.
* Currently, we only bother with that for text-format output.
Nonetheless, it's broken.
So I spent some time hacking on this and came up with the attached.
It's noticeably more verbose than your patch, but it keeps the
output-format-aware code at what seems to me to be a maintainable
arm's-length distance from the parallel-worker hacking. TEXT is
still a special case of course :-(.
This patch just covers the code, I'm not taking any position yet
about what to do about the tests. I did tweak the code to eliminate
the one formatting difference in select_parallel (ie put two spaces
after "Worker N:", which I think reads better anyhow), so it
passes check-world as it stands.
Thoughts?
regards, tom lane
diff --git a/src/backend/commands/explain.c b/src/backend/commands/explain.c
index d189b8d..9e965d2 100644
--- a/src/backend/commands/explain.c
+++ b/src/backend/commands/explain.c
@@ -123,11 +123,20 @@ static void ExplainSubPlans(List *plans, List *ancestors,
const char *relationship, ExplainState *es);
static void ExplainCustomChildren(CustomScanState *css,
List *ancestors, ExplainState *es);
+static ExplainWorkersState *ExplainCreateWorkersState(int num_workers);
+static void ExplainOpenWorker(int n, ExplainState *es);
+static void ExplainCloseWorker(int n, ExplainState *es);
+static void ExplainFlushWorkersState(ExplainState *es);
static void ExplainProperty(const char *qlabel, const char *unit,
const char *value, bool numeric, ExplainState *es);
+static void ExplainOpenSetAsideGroup(const char *objtype, const char *labelname,
+ bool labeled, int depth, ExplainState *es);
+static void ExplainSaveGroup(ExplainState *es, int depth, int *state_save);
+static void ExplainRestoreGroup(ExplainState *es, int depth, int *state_save);
static void ExplainDummyGroup(const char *objtype, const char *labelname,
ExplainState *es);
static void ExplainXMLTag(const char *tagname, int flags, ExplainState *es);
+static void ExplainIndentText(ExplainState *es);
static void ExplainJSONLineEnding(ExplainState *es);
static void ExplainYAMLLineStarting(ExplainState *es);
static void escape_yaml(StringInfo buf, const char *str);
@@ -827,7 +836,7 @@ ExplainPrintJIT(ExplainState *es, int jit_flags,
/* for higher density, open code the text output format */
if (es->format == EXPLAIN_FORMAT_TEXT)
{
- appendStringInfoSpaces(es->str, es->indent * 2);
+ ExplainIndentText(es);
if (for_workers)
appendStringInfo(es->str, "JIT for worker %u:\n", worker_num);
else
@@ -836,7 +845,7 @@ ExplainPrintJIT(ExplainState *es, int jit_flags,
ExplainPropertyInteger("Functions", NULL, ji->created_functions, es);
- appendStringInfoSpaces(es->str, es->indent * 2);
+ ExplainIndentText(es);
appendStringInfo(es->str, "Options: %s %s, %s %s, %s %s, %s %s\n",
"Inlining", jit_flags & PGJIT_INLINE ? "true" : "false",
"Optimization", jit_flags & PGJIT_OPT3 ? "true" : "false",
@@ -845,7 +854,7 @@ ExplainPrintJIT(ExplainState *es, int jit_flags,
if (es->analyze && es->timing)
{
- appendStringInfoSpaces(es->str, es->indent * 2);
+ ExplainIndentText(es);
appendStringInfo(es->str,
"Timing: %s %.3f ms, %s %.3f ms, %s %.3f ms, %s %.3f ms, %s %.3f ms\n",
"Generation", 1000.0 * INSTR_TIME_GET_DOUBLE(ji->generation_counter),
@@ -1074,9 +1083,10 @@ ExplainPreScanNode(PlanState *planstate, Bitmapset **rels_used)
* optional name to be attached to the node.
*
* In text format, es->indent is controlled in this function since we only
- * want it to change at plan-node boundaries. In non-text formats, es->indent
- * corresponds to the nesting depth of logical output groups, and therefore
- * is controlled by ExplainOpenGroup/ExplainCloseGroup.
+ * want it to change at plan-node boundaries (but a few subroutines will
+ * transiently increment it). In non-text formats, es->indent corresponds
+ * to the nesting depth of logical output groups, and therefore is controlled
+ * by ExplainOpenGroup/ExplainCloseGroup.
*/
static void
ExplainNode(PlanState *planstate, List *ancestors,
@@ -1090,9 +1100,20 @@ ExplainNode(PlanState *planstate, List *ancestors,
const char *partialmode = NULL;
const char *operation = NULL;
const char *custom_name = NULL;
+ ExplainWorkersState *save_workers_state = es->workers_state;
int save_indent = es->indent;
bool haschildren;
+ /*
+ * Prepare per-worker output buffers, if needed. We'll append the data in
+ * these to the main output string further down.
+ */
+ if (planstate->worker_instrument && es->analyze && !es->hide_workers)
+ es->workers_state = ExplainCreateWorkersState(planstate->worker_instrument->num_workers);
+ else
+ es->workers_state = NULL;
+
+ /* Identify plan node type, and print generic details */
switch (nodeTag(plan))
{
case T_Result:
@@ -1324,13 +1345,13 @@ ExplainNode(PlanState *planstate, List *ancestors,
{
if (plan_name)
{
- appendStringInfoSpaces(es->str, es->indent * 2);
+ ExplainIndentText(es);
appendStringInfo(es->str, "%s\n", plan_name);
es->indent++;
}
if (es->indent)
{
- appendStringInfoSpaces(es->str, es->indent * 2);
+ ExplainIndentText(es);
appendStringInfoString(es->str, "-> ");
es->indent += 2;
}
@@ -1574,6 +1595,56 @@ ExplainNode(PlanState *planstate, List *ancestors,
if (es->format == EXPLAIN_FORMAT_TEXT)
appendStringInfoChar(es->str, '\n');
+ /* prepare per-worker general execution details */
+ if (es->workers_state && es->verbose)
+ {
+ WorkerInstrumentation *w = planstate->worker_instrument;
+
+ for (int n = 0; n < w->num_workers; n++)
+ {
+ Instrumentation *instrument = &w->instrument[n];
+ double nloops = instrument->nloops;
+ double startup_ms;
+ double total_ms;
+ double rows;
+
+ if (nloops <= 0)
+ continue;
+ startup_ms = 1000.0 * instrument->startup / nloops;
+ total_ms = 1000.0 * instrument->total / nloops;
+ rows = instrument->ntuples / nloops;
+
+ ExplainOpenWorker(n, es);
+
+ if (es->format == EXPLAIN_FORMAT_TEXT)
+ {
+ ExplainIndentText(es);
+ if (es->timing)
+ appendStringInfo(es->str,
+ "actual time=%.3f..%.3f rows=%.0f loops=%.0f\n",
+ startup_ms, total_ms, rows, nloops);
+ else
+ appendStringInfo(es->str,
+ "actual rows=%.0f loops=%.0f\n",
+ rows, nloops);
+ }
+ else
+ {
+ if (es->timing)
+ {
+ ExplainPropertyFloat("Actual Startup Time", "ms",
+ startup_ms, 3, es);
+ ExplainPropertyFloat("Actual Total Time", "ms",
+ total_ms, 3, es);
+ }
+ ExplainPropertyFloat("Actual Rows", NULL, rows, 0, es);
+ ExplainPropertyFloat("Actual Loops", NULL, nloops, 0, es);
+ }
+
+ ExplainCloseWorker(n, es);
+ }
+ }
+
/* target list */
if (es->verbose)
show_plan_tlist(planstate, ancestors, es);
@@ -1885,76 +1956,30 @@ ExplainNode(PlanState *planstate, List *ancestors,
if (es->buffers && planstate->instrument)
show_buffer_usage(es, &planstate->instrument->bufusage);
- /* Show worker detail */
- if (es->analyze && es->verbose && !es->hide_workers &&
- planstate->worker_instrument)
+ /* Prepare per-worker buffer usage */
+ if (es->workers_state && es->buffers && es->verbose)
{
WorkerInstrumentation *w = planstate->worker_instrument;
- bool opened_group = false;
- int n;
- for (n = 0; n < w->num_workers; ++n)
+ for (int n = 0; n < w->num_workers; n++)
{
Instrumentation *instrument = &w->instrument[n];
double nloops = instrument->nloops;
- double startup_ms;
- double total_ms;
- double rows;
if (nloops <= 0)
continue;
- startup_ms = 1000.0 * instrument->startup / nloops;
- total_ms = 1000.0 * instrument->total / nloops;
- rows = instrument->ntuples / nloops;
- if (es->format == EXPLAIN_FORMAT_TEXT)
- {
- appendStringInfoSpaces(es->str, es->indent * 2);
- appendStringInfo(es->str, "Worker %d: ", n);
- if (es->timing)
- appendStringInfo(es->str,
- "actual time=%.3f..%.3f rows=%.0f loops=%.0f\n",
- startup_ms, total_ms, rows, nloops);
- else
- appendStringInfo(es->str,
- "actual rows=%.0f loops=%.0f\n",
- rows, nloops);
- es->indent++;
- if (es->buffers)
- show_buffer_usage(es, &instrument->bufusage);
- es->indent--;
- }
- else
- {
- if (!opened_group)
- {
- ExplainOpenGroup("Workers", "Workers", false, es);
- opened_group = true;
- }
- ExplainOpenGroup("Worker", NULL, true, es);
- ExplainPropertyInteger("Worker Number", NULL, n, es);
-
- if (es->timing)
- {
- ExplainPropertyFloat("Actual Startup Time", "ms",
- startup_ms, 3, es);
- ExplainPropertyFloat("Actual Total Time", "ms",
- total_ms, 3, es);
- }
- ExplainPropertyFloat("Actual Rows", NULL, rows, 0, es);
- ExplainPropertyFloat("Actual Loops", NULL, nloops, 0, es);
-
- if (es->buffers)
- show_buffer_usage(es, &instrument->bufusage);
-
- ExplainCloseGroup("Worker", NULL, true, es);
- }
+ ExplainOpenWorker(n, es);
+ show_buffer_usage(es, &instrument->bufusage);
+ ExplainCloseWorker(n, es);
}
-
- if (opened_group)
- ExplainCloseGroup("Workers", "Workers", false, es);
}
+ /* Show per-worker details, then pop that stack */
+ if (es->workers_state)
+ ExplainFlushWorkersState(es);
+ es->workers_state = save_workers_state;
+
/* Get ready to display the child plans */
haschildren = planstate->initPlan ||
outerPlanState(planstate) ||
@@ -2525,7 +2550,7 @@ show_tablesample(TableSampleClause *tsc, PlanState *planstate,
{
bool first = true;
- appendStringInfoSpaces(es->str, es->indent * 2);
+ ExplainIndentText(es);
appendStringInfo(es->str, "Sampling: %s (", method_name);
foreach(lc, params)
{
@@ -2572,7 +2597,7 @@ show_sort_info(SortState *sortstate, ExplainState *es)
if (es->format == EXPLAIN_FORMAT_TEXT)
{
- appendStringInfoSpaces(es->str, es->indent * 2);
+ ExplainIndentText(es);
appendStringInfo(es->str, "Sort Method: %s %s: %ldkB\n",
sortMethod, spaceType, spaceUsed);
}
@@ -2588,12 +2613,14 @@ show_sort_info(SortState *sortstate, ExplainState *es)
* You might think we should just skip this stanza entirely when
* es->hide_workers is true, but then we'd get no sort-method output at
* all. We have to make it look like worker 0's data is top-level data.
- * Currently, we only bother with that for text-format output.
+ * This is easily done by just skipping the OpenWorker/CloseWorker calls.
+ * Currently, we don't worry about the possibility that there are multiple
+ * workers in such a case; if there are, duplicate output fields will be
+ * emitted.
*/
if (sortstate->shared_info != NULL)
{
int n;
- bool opened_group = false;
for (n = 0; n < sortstate->shared_info->num_workers; n++)
{
@@ -2609,32 +2636,26 @@ show_sort_info(SortState *sortstate, ExplainState *es)
spaceType = tuplesort_space_type_name(sinstrument->spaceType);
spaceUsed = sinstrument->spaceUsed;
+ if (es->workers_state)
+ ExplainOpenWorker(n, es);
+
if (es->format == EXPLAIN_FORMAT_TEXT)
{
- appendStringInfoSpaces(es->str, es->indent * 2);
- if (n > 0 || !es->hide_workers)
- appendStringInfo(es->str, "Worker %d: ", n);
+ ExplainIndentText(es);
appendStringInfo(es->str,
"Sort Method: %s %s: %ldkB\n",
sortMethod, spaceType, spaceUsed);
}
else
{
- if (!opened_group)
- {
- ExplainOpenGroup("Workers", "Workers", false, es);
- opened_group = true;
- }
- ExplainOpenGroup("Worker", NULL, true, es);
- ExplainPropertyInteger("Worker Number", NULL, n, es);
ExplainPropertyText("Sort Method", sortMethod, es);
ExplainPropertyInteger("Sort Space Used", "kB", spaceUsed, es);
ExplainPropertyText("Sort Space Type", spaceType, es);
- ExplainCloseGroup("Worker", NULL, true, es);
}
+
+ if (es->workers_state)
+ ExplainCloseWorker(n, es);
}
- if (opened_group)
- ExplainCloseGroup("Workers", "Workers", false, es);
}
}
@@ -2721,7 +2742,7 @@ show_hash_info(HashState *hashstate, ExplainState *es)
else if (hinstrument.nbatch_original != hinstrument.nbatch ||
hinstrument.nbuckets_original != hinstrument.nbuckets)
{
- appendStringInfoSpaces(es->str, es->indent * 2);
+ ExplainIndentText(es);
appendStringInfo(es->str,
"Buckets: %d (originally %d) Batches: %d (originally %d) Memory Usage: %ldkB\n",
hinstrument.nbuckets,
@@ -2732,7 +2753,7 @@ show_hash_info(HashState *hashstate, ExplainState *es)
}
else
{
- appendStringInfoSpaces(es->str, es->indent * 2);
+ ExplainIndentText(es);
appendStringInfo(es->str,
"Buckets: %d Batches: %d Memory Usage: %ldkB\n",
hinstrument.nbuckets, hinstrument.nbatch,
@@ -2758,7 +2779,7 @@ show_tidbitmap_info(BitmapHeapScanState *planstate, ExplainState *es)
{
if (planstate->exact_pages > 0 || planstate->lossy_pages > 0)
{
- appendStringInfoSpaces(es->str, es->indent * 2);
+ ExplainIndentText(es);
appendStringInfoString(es->str, "Heap Blocks:");
if (planstate->exact_pages > 0)
appendStringInfo(es->str, " exact=%ld", planstate->exact_pages);
@@ -2894,7 +2915,7 @@ show_buffer_usage(ExplainState *es, const BufferUsage *usage)
/* Show only positive counter values. */
if (has_shared || has_local || has_temp)
{
- appendStringInfoSpaces(es->str, es->indent * 2);
+ ExplainIndentText(es);
appendStringInfoString(es->str, "Buffers:");
if (has_shared)
@@ -2949,7 +2970,7 @@ show_buffer_usage(ExplainState *es, const BufferUsage *usage)
/* As above, show only positive counter values. */
if (has_timing)
{
- appendStringInfoSpaces(es->str, es->indent * 2);
+ ExplainIndentText(es);
appendStringInfoString(es->str, "I/O Timings:");
if (!INSTR_TIME_IS_ZERO(usage->blk_read_time))
appendStringInfo(es->str, " read=%0.3f",
@@ -3237,7 +3258,7 @@ show_modifytable_info(ModifyTableState *mtstate, List *ancestors,
*/
if (es->format == EXPLAIN_FORMAT_TEXT)
{
- appendStringInfoSpaces(es->str, es->indent * 2);
+ ExplainIndentText(es);
appendStringInfoString(es->str,
fdwroutine ? foperation : operation);
}
@@ -3427,6 +3448,150 @@ ExplainCustomChildren(CustomScanState *css, List *ancestors, ExplainState *es)
}
/*
+ * Create a per-plan-node workspace for collecting per-worker data.
+ */
+static ExplainWorkersState *
+ExplainCreateWorkersState(int num_workers)
+{
+ ExplainWorkersState *wstate;
+
+ wstate = (ExplainWorkersState *) palloc(sizeof(ExplainWorkersState));
+ wstate->num_workers = num_workers;
+ wstate->worker_inited = (bool *) palloc0(num_workers * sizeof(bool));
+ wstate->worker_str = (StringInfoData *)
+ palloc0(num_workers * sizeof(StringInfoData));
+ wstate->worker_state_save = (int *) palloc(num_workers * sizeof(int));
+ return wstate;
+}
+
+/*
+ * Begin or resume output into the set-aside group for worker N.
+ */
+static void
+ExplainOpenWorker(int n, ExplainState *es)
+{
+ ExplainWorkersState *wstate = es->workers_state;
+
+ Assert(wstate);
+ Assert(n >= 0 && n < wstate->num_workers);
+
+ /* Save prior output pointer */
+ wstate->prev_str = es->str;
+
+ if (!wstate->worker_inited[n])
+ {
+ /* First time through, so create the buffer for this worker */
+ initStringInfo(&wstate->worker_str[n]);
+ es->str = &wstate->worker_str[n];
+
+ /*
+ * Push suitable initial formatting state for this worker's field
+ * group. We allow one extra logical nesting level, since this group
+ * will eventually be wrapped in an outer "Workers" group.
+ */
+ ExplainOpenSetAsideGroup("Worker", NULL, true, 2, es);
+
+ /*
+ * In non-TEXT formats, we always emit a "Worker Number" field even if
+ * there's no other data for this worker.
+ */
+ if (es->format != EXPLAIN_FORMAT_TEXT)
+ ExplainPropertyInteger("Worker Number", NULL, n, es);
+
+ wstate->worker_inited[n] = true;
+ }
+ else
+ {
+ /* Resuming output for a worker we've already emitted some data for */
+ es->str = &wstate->worker_str[n];
+
+ /* Restore formatting state saved by last ExplainCloseWorker() */
+ ExplainRestoreGroup(es, 2, &wstate->worker_state_save[n]);
+ }
+
+ /*
+ * In TEXT format, prefix the first output line for this worker with
+ * "Worker N:". Then, any additional lines should be indented one more
+ * stop than the "Worker N" line is.
+ */
+ if (es->format == EXPLAIN_FORMAT_TEXT)
+ {
+ if (es->str->len == 0)
+ {
+ ExplainIndentText(es);
+ appendStringInfo(es->str, "Worker %d: ", n);
+ }
+
+ es->indent++;
+ }
+}
+
+/*
+ * End output for worker N --- must pair with previous ExplainOpenWorker call
+ */
+static void
+ExplainCloseWorker(int n, ExplainState *es)
+{
+ ExplainWorkersState *wstate = es->workers_state;
+
+ Assert(wstate);
+ Assert(n >= 0 && n < wstate->num_workers);
+ Assert(wstate->worker_inited[n]);
+
+ /*
+ * Save formatting state in case we do another ExplainOpenWorker(), then
+ * pop the formatting stack.
+ */
+ ExplainSaveGroup(es, 2, &wstate->worker_state_save[n]);
+
+ /*
+ * In TEXT format, if we didn't actually produce any output line(s) then
+ * truncate off the partial line (this avoids bogus output if, for
+ * instance, show_buffer_usage chooses not to print anything). Also fix
+ * up the indent level.
+ */
+ if (es->format == EXPLAIN_FORMAT_TEXT)
+ {
+ while (es->str->len > 0 && es->str->data[es->str->len - 1] != '\n')
+ es->str->data[--(es->str->len)] = '\0';
+
+ es->indent--;
+ }
+
+ /* Restore prior output pointer */
+ es->str = wstate->prev_str;
+}
+
+/*
+ * Print per-worker info for current node, then free the ExplainWorkersState.
+ */
+static void
+ExplainFlushWorkersState(ExplainState *es)
+{
+ ExplainWorkersState *wstate = es->workers_state;
+
+ ExplainOpenGroup("Workers", "Workers", false, es);
+ for (int i = 0; i < wstate->num_workers; i++)
+ {
+ if (wstate->worker_inited[i])
+ {
+ /* This must match previous ExplainOpenSetAsideGroup call */
+ ExplainOpenGroup("Worker", NULL, true, es);
+ appendStringInfoString(es->str, wstate->worker_str[i].data);
+ ExplainCloseGroup("Worker", NULL, true, es);
+
+ pfree(wstate->worker_str[i].data);
+ }
+ }
+ ExplainCloseGroup("Workers", "Workers", false, es);
+
+ pfree(wstate->worker_inited);
+ pfree(wstate->worker_str);
+ pfree(wstate->worker_state_save);
+ pfree(wstate);
+}
+
+/*
* Explain a property, such as sort keys or targets, that takes the form of
* a list of unlabeled items. "data" is a list of C strings.
*/
@@ -3439,7 +3604,7 @@ ExplainPropertyList(const char *qlabel, List *data, ExplainState *es)
switch (es->format)
{
case EXPLAIN_FORMAT_TEXT:
- appendStringInfoSpaces(es->str, es->indent * 2);
+ ExplainIndentText(es);
appendStringInfo(es->str, "%s: ", qlabel);
foreach(lc, data)
{
@@ -3560,7 +3725,7 @@ ExplainProperty(const char *qlabel, const char *unit, const char *value,
switch (es->format)
{
case EXPLAIN_FORMAT_TEXT:
- appendStringInfoSpaces(es->str, es->indent * 2);
+ ExplainIndentText(es);
if (unit)
appendStringInfo(es->str, "%s: %s %s\n", qlabel, value, unit);
else
@@ -3752,6 +3917,117 @@ ExplainCloseGroup(const char *objtype, const char *labelname,
}
/*
+ * Open a group of related objects, without emitting actual data.
+ *
+ * Prepare the formatting state as though we were beginning a group with
+ * the identified properties, but don't actually emit anything. Output
+ * subsequent to this call can be redirected into a separate output buffer,
+ * and then eventually appended to the main output buffer after doing a
+ * regular ExplainOpenGroup call (with the same parameters).
+ *
+ * The extra "depth" parameter is the new group's depth compared to current.
+ * It could be more than one, in case the eventual output will be enclosed
+ * in additional nesting group levels. We assume we don't need to track
+ * formatting state for those levels while preparing this group's output.
+ *
+ * There is no ExplainCloseSetAsideGroup --- in current usage, we always
+ * pop this state with ExplainSaveGroup.
+ */
+static void
+ExplainOpenSetAsideGroup(const char *objtype, const char *labelname,
+ bool labeled, int depth, ExplainState *es)
+{
+ switch (es->format)
+ {
+ case EXPLAIN_FORMAT_TEXT:
+ /* nothing to do */
+ break;
+
+ case EXPLAIN_FORMAT_XML:
+ es->indent += depth;
+ break;
+
+ case EXPLAIN_FORMAT_JSON:
+ es->grouping_stack = lcons_int(0, es->grouping_stack);
+ es->indent += depth;
+ break;
+
+ case EXPLAIN_FORMAT_YAML:
+ if (labelname)
+ es->grouping_stack = lcons_int(1, es->grouping_stack);
+ else
+ es->grouping_stack = lcons_int(0, es->grouping_stack);
+ es->indent += depth;
+ break;
+ }
+}
+
+/*
+ * Pop one level of grouping state, allowing for a re-push later.
+ *
+ * This is typically used after ExplainOpenSetAsideGroup; pass the
+ * same "depth" used for that.
+ *
+ * This should not emit any output. If state needs to be saved,
+ * save it at *state_save. Currently, an integer save area is sufficient
+ * for all formats, but we might need to revisit that someday.
+ */
+static void
+ExplainSaveGroup(ExplainState *es, int depth, int *state_save)
+{
+ switch (es->format)
+ {
+ case EXPLAIN_FORMAT_TEXT:
+ /* nothing to do */
+ break;
+
+ case EXPLAIN_FORMAT_XML:
+ es->indent -= depth;
+ break;
+
+ case EXPLAIN_FORMAT_JSON:
+ es->indent -= depth;
+ *state_save = linitial_int(es->grouping_stack);
+ es->grouping_stack = list_delete_first(es->grouping_stack);
+ break;
+
+ case EXPLAIN_FORMAT_YAML:
+ es->indent -= depth;
+ *state_save = linitial_int(es->grouping_stack);
+ es->grouping_stack = list_delete_first(es->grouping_stack);
+ break;
+ }
+}
+
+/*
+ * Re-push one level of grouping state, undoing the effects of ExplainSaveGroup.
+ */
+static void
+ExplainRestoreGroup(ExplainState *es, int depth, int *state_save)
+{
+ switch (es->format)
+ {
+ case EXPLAIN_FORMAT_TEXT:
+ /* nothing to do */
+ break;
+
+ case EXPLAIN_FORMAT_XML:
+ es->indent += depth;
+ break;
+
+ case EXPLAIN_FORMAT_JSON:
+ es->grouping_stack = lcons_int(*state_save, es->grouping_stack);
+ es->indent += depth;
+ break;
+
+ case EXPLAIN_FORMAT_YAML:
+ es->grouping_stack = lcons_int(*state_save, es->grouping_stack);
+ es->indent += depth;
+ break;
+ }
+}
+
+/*
* Emit a "dummy" group that never has any members.
*
* objtype is the type of the group object, labelname is its label within
@@ -3913,6 +4189,21 @@ ExplainXMLTag(const char *tagname, int flags, ExplainState *es)
}
/*
+ * Indent a text-format line.
+ *
+ * We indent by two spaces per indentation level. However, when emitting
+ * data for a parallel worker there might already be data on the current line
+ * (cf. ExplainOpenWorker); in that case, don't indent any more.
+ */
+static void
+ExplainIndentText(ExplainState *es)
+{
+ Assert(es->format == EXPLAIN_FORMAT_TEXT);
+ if (es->str->len == 0 || es->str->data[es->str->len - 1] == '\n')
+ appendStringInfoSpaces(es->str, es->indent * 2);
+}
+
+/*
* Emit a JSON line ending.
*
* JSON requires a comma after each property but the last. To facilitate this,
diff --git a/src/include/commands/explain.h b/src/include/commands/explain.h
index 45027a7..853e206 100644
--- a/src/include/commands/explain.h
+++ b/src/include/commands/explain.h
@@ -25,6 +25,15 @@ typedef enum ExplainFormat
EXPLAIN_FORMAT_YAML
} ExplainFormat;
+typedef struct ExplainWorkersState
+{
+ int num_workers; /* # of worker processes the plan used */
+ bool *worker_inited; /* per-worker state-initialized flags */
+ StringInfoData *worker_str; /* per-worker transient output buffers */
+ int *worker_state_save; /* per-worker grouping state save areas */
+ StringInfo prev_str; /* saved output buffer while redirecting */
+} ExplainWorkersState;
+
typedef struct ExplainState
{
StringInfo str; /* output buffer */
@@ -47,6 +56,8 @@ typedef struct ExplainState
List *deparse_cxt; /* context list for deparsing expressions */
Bitmapset *printed_subplans; /* ids of SubPlans we've printed */
bool hide_workers; /* set if we find an invisible Gather */
+ /* state related to the current plan node */
+ ExplainWorkersState *workers_state; /* needed if parallel plan */
} ExplainState;
/* Hook for plugins to get control in ExplainOneQuery() */
