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Commitd4382c4

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Extend EXPLAIN to allow generic options to be specified.
The original syntax made it difficult to add options without making theminto reserved words. This change parenthesizes the options to avoid thatproblem, and makes provision for an explicit (and perhaps non-Boolean)value for each option. The original syntax is still supported, but onlyfor the two original options ANALYZE and VERBOSE.As a test case, add a COSTS option that can suppress the planner costestimates. This may be useful for including EXPLAIN output in the regressiontests, which are otherwise unable to cope with cross-platform variations incost estimates.Robert Haas
1 parenta07e5ac commitd4382c4

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12 files changed

+282
-156
lines changed

12 files changed

+282
-156
lines changed

‎contrib/auto_explain/auto_explain.c

Lines changed: 11 additions & 10 deletions
Original file line numberDiff line numberDiff line change
@@ -6,7 +6,7 @@
66
* Copyright (c) 2008-2009, PostgreSQL Global Development Group
77
*
88
* IDENTIFICATION
9-
* $PostgreSQL: pgsql/contrib/auto_explain/auto_explain.c,v 1.5 2009/06/11 14:48:50 momjian Exp $
9+
* $PostgreSQL: pgsql/contrib/auto_explain/auto_explain.c,v 1.6 2009/07/26 23:34:17 tgl Exp $
1010
*
1111
*-------------------------------------------------------------------------
1212
*/
@@ -196,16 +196,17 @@ explain_ExecutorEnd(QueryDesc *queryDesc)
196196
msec=queryDesc->totaltime->total*1000.0;
197197
if (msec >=auto_explain_log_min_duration)
198198
{
199-
StringInfoDatabuf;
199+
ExplainStatees;
200200

201-
initStringInfo(&buf);
202-
ExplainPrintPlan(&buf,queryDesc,
203-
queryDesc->doInstrument&&auto_explain_log_analyze,
204-
auto_explain_log_verbose);
201+
ExplainInitState(&es);
202+
es.analyze= (queryDesc->doInstrument&&auto_explain_log_analyze);
203+
es.verbose=auto_explain_log_verbose;
204+
205+
ExplainPrintPlan(&es,queryDesc);
205206

206207
/* Remove last line break */
207-
if (buf.len>0&&buf.data[buf.len-1]=='\n')
208-
buf.data[--buf.len]='\0';
208+
if (es.str->len>0&&es.str->data[es.str->len-1]=='\n')
209+
es.str->data[--es.str->len]='\0';
209210

210211
/*
211212
* Note: we rely on the existing logging of context or
@@ -215,9 +216,9 @@ explain_ExecutorEnd(QueryDesc *queryDesc)
215216
*/
216217
ereport(LOG,
217218
(errmsg("duration: %.3f ms plan:\n%s",
218-
msec,buf.data)));
219+
msec,es.str->data)));
219220

220-
pfree(buf.data);
221+
pfree(es.str->data);
221222
}
222223
}
223224

‎doc/src/sgml/ref/explain.sgml

Lines changed: 53 additions & 11 deletions
Original file line numberDiff line numberDiff line change
@@ -1,5 +1,5 @@
11
<!--
2-
$PostgreSQL: pgsql/doc/src/sgml/ref/explain.sgml,v 1.44 2008/11/14 10:22:47 petere Exp $
2+
$PostgreSQL: pgsql/doc/src/sgml/ref/explain.sgml,v 1.45 2009/07/26 23:34:17 tgl Exp $
33
PostgreSQL documentation
44
-->
55

@@ -31,6 +31,7 @@ PostgreSQL documentation
3131

3232
<refsynopsisdiv>
3333
<synopsis>
34+
EXPLAIN [ ( { ANALYZE <replaceable class="parameter">boolean</replaceable> | VERBOSE <replaceable class="parameter">boolean</replaceable> | COSTS <replaceable class="parameter">boolean</replaceable> } [, ...] ) ] <replaceable class="parameter">statement</replaceable>
3435
EXPLAIN [ ANALYZE ] [ VERBOSE ] <replaceable class="parameter">statement</replaceable>
3536
</synopsis>
3637
</refsynopsisdiv>
@@ -89,6 +90,14 @@ ROLLBACK;
8990
</programlisting>
9091
</para>
9192
</important>
93+
94+
<para>
95+
Only the <literal>ANALYZE</literal> and <literal>VERBOSE</literal> options
96+
can be specified, and only in that order, without surrounding the option
97+
list in parentheses. Prior to <productname>PostgreSQL</productname> 8.5,
98+
the unparenthesized syntax was the only one supported. It is expected that
99+
all new options will be supported only in the parenthesized syntax.
100+
</para>
92101
</refsect1>
93102

94103
<refsect1>
@@ -99,7 +108,8 @@ ROLLBACK;
99108
<term><literal>ANALYZE</literal></term>
100109
<listitem>
101110
<para>
102-
Carry out the command and show the actual run times.
111+
Carry out the command and show the actual run times. This
112+
parameter defaults to <command>FALSE</command>.
103113
</para>
104114
</listitem>
105115
</varlistentry>
@@ -108,7 +118,33 @@ ROLLBACK;
108118
<term><literal>VERBOSE</literal></term>
109119
<listitem>
110120
<para>
111-
Include the output column list for each node in the plan tree.
121+
Include the output column list for each node in the plan tree. This
122+
parameter defaults to <command>FALSE</command>.
123+
</para>
124+
</listitem>
125+
</varlistentry>
126+
127+
<varlistentry>
128+
<term><literal>COSTS</literal></term>
129+
<listitem>
130+
<para>
131+
Include information on the estimated startup and total cost of each
132+
plan node, as well as the estimated number of rows and the estimated
133+
width of each row. This parameter defaults to <command>TRUE</command>.
134+
</para>
135+
</listitem>
136+
</varlistentry>
137+
138+
<varlistentry>
139+
<term><replaceable class="parameter">boolean</replaceable></term>
140+
<listitem>
141+
<para>
142+
Specifies whether the selected option should be turned on or off.
143+
You can write <literal>TRUE</literal>, <literal>ON</>, or
144+
<literal>1</literal> to enable the option, and <literal>FALSE</literal>,
145+
<literal>OFF</>, or <literal>0</literal> to disable it. The
146+
<replaceable class="parameter">boolean</replaceable> value can also
147+
be omitted, in which case <literal>TRUE</literal> is assumed.
112148
</para>
113149
</listitem>
114150
</varlistentry>
@@ -149,14 +185,6 @@ ROLLBACK;
149185
might be chosen.
150186
</para>
151187

152-
<para>
153-
Genetic query optimization (<acronym>GEQO</acronym>) randomly tests
154-
execution plans. Therefore, when the number of join relations
155-
exceeds <xref linkend="guc-geqo-threshold"> causing genetic query
156-
optimization to be used, the execution plan is likely to change
157-
each time the statement is executed.
158-
</para>
159-
160188
<para>
161189
In order to measure the run-time cost of each node in the execution
162190
plan, the current implementation of <command>EXPLAIN
@@ -201,6 +229,20 @@ EXPLAIN SELECT * FROM foo WHERE i = 4;
201229
</programlisting>
202230
</para>
203231

232+
<para>
233+
Here is the same plan with costs suppressed:
234+
235+
<programlisting>
236+
EXPLAIN (COSTS FALSE) SELECT * FROM foo WHERE i = 4;
237+
238+
QUERY PLAN
239+
----------------------------
240+
Index Scan using fi on foo
241+
Index Cond: (i = 4)
242+
(2 rows)
243+
</programlisting>
244+
</para>
245+
204246
<para>
205247
Here is an example of a query plan for a query using an aggregate
206248
function:

‎src/backend/commands/define.c

Lines changed: 10 additions & 3 deletions
Original file line numberDiff line numberDiff line change
@@ -9,7 +9,7 @@
99
*
1010
*
1111
* IDENTIFICATION
12-
* $PostgreSQL: pgsql/src/backend/commands/define.c,v 1.104 2009/04/04 21:12:31 tgl Exp $
12+
* $PostgreSQL: pgsql/src/backend/commands/define.c,v 1.105 2009/07/26 23:34:17 tgl Exp $
1313
*
1414
* DESCRIPTION
1515
* The "DefineFoo" routines take the parse tree and pick out the
@@ -133,7 +133,7 @@ defGetBoolean(DefElem *def)
133133
return true;
134134

135135
/*
136-
* Allow 0, 1, "true", "false"
136+
* Allow 0, 1, "true", "false", "on", "off"
137137
*/
138138
switch (nodeTag(def->arg))
139139
{
@@ -153,11 +153,18 @@ defGetBoolean(DefElem *def)
153153
{
154154
char*sval=defGetString(def);
155155

156+
/*
157+
* The set of strings accepted here should match up with
158+
* the grammar's opt_boolean production.
159+
*/
156160
if (pg_strcasecmp(sval,"true")==0)
157161
return true;
158162
if (pg_strcasecmp(sval,"false")==0)
159163
return false;
160-
164+
if (pg_strcasecmp(sval,"on")==0)
165+
return true;
166+
if (pg_strcasecmp(sval,"off")==0)
167+
return false;
161168
}
162169
break;
163170
}

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