LCOV - code coverage report
Current view: top level - src/backend/commands - explain_format.c (source / functions) Coverage Total Hit
Test: PostgreSQL 19devel Lines: 76.1 % 326 248
Test Date: 2026-03-22 08:15:57 Functions: 100.0 % 22 22
Legend: Lines:     hit not hit

            Line data    Source code
       1              : /*-------------------------------------------------------------------------
       2              :  *
       3              :  * explain_format.c
       4              :  *    Format routines for explaining query execution plans
       5              :  *
       6              :  * Portions Copyright (c) 1996-2026, PostgreSQL Global Development Group
       7              :  * Portions Copyright (c) 1994-5, Regents of the University of California
       8              :  *
       9              :  * IDENTIFICATION
      10              :  *    src/backend/commands/explain_format.c
      11              :  *
      12              :  *-------------------------------------------------------------------------
      13              :  */
      14              : #include "postgres.h"
      15              : 
      16              : #include "commands/explain.h"
      17              : #include "commands/explain_format.h"
      18              : #include "commands/explain_state.h"
      19              : #include "utils/json.h"
      20              : #include "utils/xml.h"
      21              : 
      22              : /* OR-able flags for ExplainXMLTag() */
      23              : #define X_OPENING 0
      24              : #define X_CLOSING 1
      25              : #define X_CLOSE_IMMEDIATE 2
      26              : #define X_NOWHITESPACE 4
      27              : 
      28              : static void ExplainJSONLineEnding(ExplainState *es);
      29              : static void ExplainXMLTag(const char *tagname, int flags, ExplainState *es);
      30              : static void ExplainYAMLLineStarting(ExplainState *es);
      31              : static void escape_yaml(StringInfo buf, const char *str);
      32              : 
      33              : /*
      34              :  * Explain a property, such as sort keys or targets, that takes the form of
      35              :  * a list of unlabeled items.  "data" is a list of C strings.
      36              :  */
      37              : void
      38        13541 : ExplainPropertyList(const char *qlabel, List *data, ExplainState *es)
      39              : {
      40              :     ListCell   *lc;
      41        13541 :     bool        first = true;
      42              : 
      43        13541 :     switch (es->format)
      44              :     {
      45        13431 :         case EXPLAIN_FORMAT_TEXT:
      46        13431 :             ExplainIndentText(es);
      47        13431 :             appendStringInfo(es->str, "%s: ", qlabel);
      48        40545 :             foreach(lc, data)
      49              :             {
      50        27114 :                 if (!first)
      51        13683 :                     appendStringInfoString(es->str, ", ");
      52        27114 :                 appendStringInfoString(es->str, (const char *) lfirst(lc));
      53        27114 :                 first = false;
      54              :             }
      55        13431 :             appendStringInfoChar(es->str, '\n');
      56        13431 :             break;
      57              : 
      58            2 :         case EXPLAIN_FORMAT_XML:
      59            2 :             ExplainXMLTag(qlabel, X_OPENING, es);
      60            5 :             foreach(lc, data)
      61              :             {
      62              :                 char       *str;
      63              : 
      64            3 :                 appendStringInfoSpaces(es->str, es->indent * 2 + 2);
      65            3 :                 appendStringInfoString(es->str, "<Item>");
      66            3 :                 str = escape_xml((const char *) lfirst(lc));
      67            3 :                 appendStringInfoString(es->str, str);
      68            3 :                 pfree(str);
      69            3 :                 appendStringInfoString(es->str, "</Item>\n");
      70              :             }
      71            2 :             ExplainXMLTag(qlabel, X_CLOSING, es);
      72            2 :             break;
      73              : 
      74          108 :         case EXPLAIN_FORMAT_JSON:
      75          108 :             ExplainJSONLineEnding(es);
      76          108 :             appendStringInfoSpaces(es->str, es->indent * 2);
      77          108 :             escape_json(es->str, qlabel);
      78          108 :             appendStringInfoString(es->str, ": [");
      79          444 :             foreach(lc, data)
      80              :             {
      81          336 :                 if (!first)
      82          228 :                     appendStringInfoString(es->str, ", ");
      83          336 :                 escape_json(es->str, (const char *) lfirst(lc));
      84          336 :                 first = false;
      85              :             }
      86          108 :             appendStringInfoChar(es->str, ']');
      87          108 :             break;
      88              : 
      89            0 :         case EXPLAIN_FORMAT_YAML:
      90            0 :             ExplainYAMLLineStarting(es);
      91            0 :             appendStringInfo(es->str, "%s: ", qlabel);
      92            0 :             foreach(lc, data)
      93              :             {
      94            0 :                 appendStringInfoChar(es->str, '\n');
      95            0 :                 appendStringInfoSpaces(es->str, es->indent * 2 + 2);
      96            0 :                 appendStringInfoString(es->str, "- ");
      97            0 :                 escape_yaml(es->str, (const char *) lfirst(lc));
      98              :             }
      99            0 :             break;
     100              :     }
     101        13541 : }
     102              : 
     103              : /*
     104              :  * Explain a property that takes the form of a list of unlabeled items within
     105              :  * another list.  "data" is a list of C strings.
     106              :  */
     107              : void
     108          460 : ExplainPropertyListNested(const char *qlabel, List *data, ExplainState *es)
     109              : {
     110              :     ListCell   *lc;
     111          460 :     bool        first = true;
     112              : 
     113          460 :     switch (es->format)
     114              :     {
     115          460 :         case EXPLAIN_FORMAT_TEXT:
     116              :         case EXPLAIN_FORMAT_XML:
     117          460 :             ExplainPropertyList(qlabel, data, es);
     118          460 :             return;
     119              : 
     120            0 :         case EXPLAIN_FORMAT_JSON:
     121            0 :             ExplainJSONLineEnding(es);
     122            0 :             appendStringInfoSpaces(es->str, es->indent * 2);
     123            0 :             appendStringInfoChar(es->str, '[');
     124            0 :             foreach(lc, data)
     125              :             {
     126            0 :                 if (!first)
     127            0 :                     appendStringInfoString(es->str, ", ");
     128            0 :                 escape_json(es->str, (const char *) lfirst(lc));
     129            0 :                 first = false;
     130              :             }
     131            0 :             appendStringInfoChar(es->str, ']');
     132            0 :             break;
     133              : 
     134            0 :         case EXPLAIN_FORMAT_YAML:
     135            0 :             ExplainYAMLLineStarting(es);
     136            0 :             appendStringInfoString(es->str, "- [");
     137            0 :             foreach(lc, data)
     138              :             {
     139            0 :                 if (!first)
     140            0 :                     appendStringInfoString(es->str, ", ");
     141            0 :                 escape_yaml(es->str, (const char *) lfirst(lc));
     142            0 :                 first = false;
     143              :             }
     144            0 :             appendStringInfoChar(es->str, ']');
     145            0 :             break;
     146              :     }
     147              : }
     148              : 
     149              : /*
     150              :  * Explain a simple property.
     151              :  *
     152              :  * If "numeric" is true, the value is a number (or other value that
     153              :  * doesn't need quoting in JSON).
     154              :  *
     155              :  * If unit is non-NULL the text format will display it after the value.
     156              :  *
     157              :  * This usually should not be invoked directly, but via one of the datatype
     158              :  * specific routines ExplainPropertyText, ExplainPropertyInteger, etc.
     159              :  */
     160              : static void
     161        52443 : ExplainProperty(const char *qlabel, const char *unit, const char *value,
     162              :                 bool numeric, ExplainState *es)
     163              : {
     164        52443 :     switch (es->format)
     165              :     {
     166        33119 :         case EXPLAIN_FORMAT_TEXT:
     167        33119 :             ExplainIndentText(es);
     168        33119 :             if (unit)
     169         3176 :                 appendStringInfo(es->str, "%s: %s %s\n", qlabel, value, unit);
     170              :             else
     171        29943 :                 appendStringInfo(es->str, "%s: %s\n", qlabel, value);
     172        33119 :             break;
     173              : 
     174          252 :         case EXPLAIN_FORMAT_XML:
     175              :             {
     176              :                 char       *str;
     177              : 
     178          252 :                 appendStringInfoSpaces(es->str, es->indent * 2);
     179          252 :                 ExplainXMLTag(qlabel, X_OPENING | X_NOWHITESPACE, es);
     180          252 :                 str = escape_xml(value);
     181          252 :                 appendStringInfoString(es->str, str);
     182          252 :                 pfree(str);
     183          252 :                 ExplainXMLTag(qlabel, X_CLOSING | X_NOWHITESPACE, es);
     184          252 :                 appendStringInfoChar(es->str, '\n');
     185              :             }
     186          252 :             break;
     187              : 
     188        18824 :         case EXPLAIN_FORMAT_JSON:
     189        18824 :             ExplainJSONLineEnding(es);
     190        18824 :             appendStringInfoSpaces(es->str, es->indent * 2);
     191        18824 :             escape_json(es->str, qlabel);
     192        18824 :             appendStringInfoString(es->str, ": ");
     193        18824 :             if (numeric)
     194        16386 :                 appendStringInfoString(es->str, value);
     195              :             else
     196         2438 :                 escape_json(es->str, value);
     197        18824 :             break;
     198              : 
     199          248 :         case EXPLAIN_FORMAT_YAML:
     200          248 :             ExplainYAMLLineStarting(es);
     201          248 :             appendStringInfo(es->str, "%s: ", qlabel);
     202          248 :             if (numeric)
     203          220 :                 appendStringInfoString(es->str, value);
     204              :             else
     205           28 :                 escape_yaml(es->str, value);
     206          248 :             break;
     207              :     }
     208        52443 : }
     209              : 
     210              : /*
     211              :  * Explain a string-valued property.
     212              :  */
     213              : void
     214        29473 : ExplainPropertyText(const char *qlabel, const char *value, ExplainState *es)
     215              : {
     216        29473 :     ExplainProperty(qlabel, NULL, value, false, es);
     217        29473 : }
     218              : 
     219              : /*
     220              :  * Explain an integer-valued property.
     221              :  */
     222              : void
     223        10102 : ExplainPropertyInteger(const char *qlabel, const char *unit, int64 value,
     224              :                        ExplainState *es)
     225              : {
     226              :     char        buf[32];
     227              : 
     228        10102 :     snprintf(buf, sizeof(buf), INT64_FORMAT, value);
     229        10102 :     ExplainProperty(qlabel, unit, buf, true, es);
     230        10102 : }
     231              : 
     232              : /*
     233              :  * Explain an unsigned integer-valued property.
     234              :  */
     235              : void
     236         1026 : ExplainPropertyUInteger(const char *qlabel, const char *unit, uint64 value,
     237              :                         ExplainState *es)
     238              : {
     239              :     char        buf[32];
     240              : 
     241         1026 :     snprintf(buf, sizeof(buf), UINT64_FORMAT, value);
     242         1026 :     ExplainProperty(qlabel, unit, buf, true, es);
     243         1026 : }
     244              : 
     245              : /*
     246              :  * Explain a float-valued property, using the specified number of
     247              :  * fractional digits.
     248              :  */
     249              : void
     250         9325 : ExplainPropertyFloat(const char *qlabel, const char *unit, double value,
     251              :                      int ndigits, ExplainState *es)
     252              : {
     253              :     char       *buf;
     254              : 
     255         9325 :     buf = psprintf("%.*f", ndigits, value);
     256         9325 :     ExplainProperty(qlabel, unit, buf, true, es);
     257         9325 :     pfree(buf);
     258         9325 : }
     259              : 
     260              : /*
     261              :  * Explain a bool-valued property.
     262              :  */
     263              : void
     264         2517 : ExplainPropertyBool(const char *qlabel, bool value, ExplainState *es)
     265              : {
     266         2517 :     ExplainProperty(qlabel, NULL, value ? "true" : "false", true, es);
     267         2517 : }
     268              : 
     269              : /*
     270              :  * Open a group of related objects.
     271              :  *
     272              :  * objtype is the type of the group object, labelname is its label within
     273              :  * a containing object (if any).
     274              :  *
     275              :  * If labeled is true, the group members will be labeled properties,
     276              :  * while if it's false, they'll be unlabeled objects.
     277              :  */
     278              : void
     279       109592 : ExplainOpenGroup(const char *objtype, const char *labelname,
     280              :                  bool labeled, ExplainState *es)
     281              : {
     282       109592 :     switch (es->format)
     283              :     {
     284       107568 :         case EXPLAIN_FORMAT_TEXT:
     285              :             /* nothing to do */
     286       107568 :             break;
     287              : 
     288           31 :         case EXPLAIN_FORMAT_XML:
     289           31 :             ExplainXMLTag(objtype, X_OPENING, es);
     290           31 :             es->indent++;
     291           31 :             break;
     292              : 
     293         1961 :         case EXPLAIN_FORMAT_JSON:
     294         1961 :             ExplainJSONLineEnding(es);
     295         1961 :             appendStringInfoSpaces(es->str, 2 * es->indent);
     296         1961 :             if (labelname)
     297              :             {
     298         1232 :                 escape_json(es->str, labelname);
     299         1232 :                 appendStringInfoString(es->str, ": ");
     300              :             }
     301         1961 :             appendStringInfoChar(es->str, labeled ? '{' : '[');
     302              : 
     303              :             /*
     304              :              * In JSON format, the grouping_stack is an integer list.  0 means
     305              :              * we've emitted nothing at this grouping level, 1 means we've
     306              :              * emitted something (and so the next item needs a comma). See
     307              :              * ExplainJSONLineEnding().
     308              :              */
     309         1961 :             es->grouping_stack = lcons_int(0, es->grouping_stack);
     310         1961 :             es->indent++;
     311         1961 :             break;
     312              : 
     313           32 :         case EXPLAIN_FORMAT_YAML:
     314              : 
     315              :             /*
     316              :              * In YAML format, the grouping stack is an integer list.  0 means
     317              :              * we've emitted nothing at this grouping level AND this grouping
     318              :              * level is unlabeled and must be marked with "- ".  See
     319              :              * ExplainYAMLLineStarting().
     320              :              */
     321           32 :             ExplainYAMLLineStarting(es);
     322           32 :             if (labelname)
     323              :             {
     324           24 :                 appendStringInfo(es->str, "%s: ", labelname);
     325           24 :                 es->grouping_stack = lcons_int(1, es->grouping_stack);
     326              :             }
     327              :             else
     328              :             {
     329            8 :                 appendStringInfoString(es->str, "- ");
     330            8 :                 es->grouping_stack = lcons_int(0, es->grouping_stack);
     331              :             }
     332           32 :             es->indent++;
     333           32 :             break;
     334              :     }
     335       109592 : }
     336              : 
     337              : /*
     338              :  * Close a group of related objects.
     339              :  * Parameters must match the corresponding ExplainOpenGroup call.
     340              :  */
     341              : void
     342       109592 : ExplainCloseGroup(const char *objtype, const char *labelname,
     343              :                   bool labeled, ExplainState *es)
     344              : {
     345       109592 :     switch (es->format)
     346              :     {
     347       107568 :         case EXPLAIN_FORMAT_TEXT:
     348              :             /* nothing to do */
     349       107568 :             break;
     350              : 
     351           31 :         case EXPLAIN_FORMAT_XML:
     352           31 :             es->indent--;
     353           31 :             ExplainXMLTag(objtype, X_CLOSING, es);
     354           31 :             break;
     355              : 
     356         1961 :         case EXPLAIN_FORMAT_JSON:
     357         1961 :             es->indent--;
     358         1961 :             appendStringInfoChar(es->str, '\n');
     359         1961 :             appendStringInfoSpaces(es->str, 2 * es->indent);
     360         1961 :             appendStringInfoChar(es->str, labeled ? '}' : ']');
     361         1961 :             es->grouping_stack = list_delete_first(es->grouping_stack);
     362         1961 :             break;
     363              : 
     364           32 :         case EXPLAIN_FORMAT_YAML:
     365           32 :             es->indent--;
     366           32 :             es->grouping_stack = list_delete_first(es->grouping_stack);
     367           32 :             break;
     368              :     }
     369       109592 : }
     370              : 
     371              : /*
     372              :  * Open a group of related objects, without emitting actual data.
     373              :  *
     374              :  * Prepare the formatting state as though we were beginning a group with
     375              :  * the identified properties, but don't actually emit anything.  Output
     376              :  * subsequent to this call can be redirected into a separate output buffer,
     377              :  * and then eventually appended to the main output buffer after doing a
     378              :  * regular ExplainOpenGroup call (with the same parameters).
     379              :  *
     380              :  * The extra "depth" parameter is the new group's depth compared to current.
     381              :  * It could be more than one, in case the eventual output will be enclosed
     382              :  * in additional nesting group levels.  We assume we don't need to track
     383              :  * formatting state for those levels while preparing this group's output.
     384              :  *
     385              :  * There is no ExplainCloseSetAsideGroup --- in current usage, we always
     386              :  * pop this state with ExplainSaveGroup.
     387              :  */
     388              : void
     389           48 : ExplainOpenSetAsideGroup(const char *objtype, const char *labelname,
     390              :                          bool labeled, int depth, ExplainState *es)
     391              : {
     392           48 :     switch (es->format)
     393              :     {
     394           16 :         case EXPLAIN_FORMAT_TEXT:
     395              :             /* nothing to do */
     396           16 :             break;
     397              : 
     398            0 :         case EXPLAIN_FORMAT_XML:
     399            0 :             es->indent += depth;
     400            0 :             break;
     401              : 
     402           32 :         case EXPLAIN_FORMAT_JSON:
     403           32 :             es->grouping_stack = lcons_int(0, es->grouping_stack);
     404           32 :             es->indent += depth;
     405           32 :             break;
     406              : 
     407            0 :         case EXPLAIN_FORMAT_YAML:
     408            0 :             if (labelname)
     409            0 :                 es->grouping_stack = lcons_int(1, es->grouping_stack);
     410              :             else
     411            0 :                 es->grouping_stack = lcons_int(0, es->grouping_stack);
     412            0 :             es->indent += depth;
     413            0 :             break;
     414              :     }
     415           48 : }
     416              : 
     417              : /*
     418              :  * Pop one level of grouping state, allowing for a re-push later.
     419              :  *
     420              :  * This is typically used after ExplainOpenSetAsideGroup; pass the
     421              :  * same "depth" used for that.
     422              :  *
     423              :  * This should not emit any output.  If state needs to be saved,
     424              :  * save it at *state_save.  Currently, an integer save area is sufficient
     425              :  * for all formats, but we might need to revisit that someday.
     426              :  */
     427              : void
     428           96 : ExplainSaveGroup(ExplainState *es, int depth, int *state_save)
     429              : {
     430           96 :     switch (es->format)
     431              :     {
     432           16 :         case EXPLAIN_FORMAT_TEXT:
     433              :             /* nothing to do */
     434           16 :             break;
     435              : 
     436            0 :         case EXPLAIN_FORMAT_XML:
     437            0 :             es->indent -= depth;
     438            0 :             break;
     439              : 
     440           80 :         case EXPLAIN_FORMAT_JSON:
     441           80 :             es->indent -= depth;
     442           80 :             *state_save = linitial_int(es->grouping_stack);
     443           80 :             es->grouping_stack = list_delete_first(es->grouping_stack);
     444           80 :             break;
     445              : 
     446            0 :         case EXPLAIN_FORMAT_YAML:
     447            0 :             es->indent -= depth;
     448            0 :             *state_save = linitial_int(es->grouping_stack);
     449            0 :             es->grouping_stack = list_delete_first(es->grouping_stack);
     450            0 :             break;
     451              :     }
     452           96 : }
     453              : 
     454              : /*
     455              :  * Re-push one level of grouping state, undoing the effects of ExplainSaveGroup.
     456              :  */
     457              : void
     458           48 : ExplainRestoreGroup(ExplainState *es, int depth, int *state_save)
     459              : {
     460           48 :     switch (es->format)
     461              :     {
     462            0 :         case EXPLAIN_FORMAT_TEXT:
     463              :             /* nothing to do */
     464            0 :             break;
     465              : 
     466            0 :         case EXPLAIN_FORMAT_XML:
     467            0 :             es->indent += depth;
     468            0 :             break;
     469              : 
     470           48 :         case EXPLAIN_FORMAT_JSON:
     471           48 :             es->grouping_stack = lcons_int(*state_save, es->grouping_stack);
     472           48 :             es->indent += depth;
     473           48 :             break;
     474              : 
     475            0 :         case EXPLAIN_FORMAT_YAML:
     476            0 :             es->grouping_stack = lcons_int(*state_save, es->grouping_stack);
     477            0 :             es->indent += depth;
     478            0 :             break;
     479              :     }
     480           48 : }
     481              : 
     482              : /*
     483              :  * Emit a "dummy" group that never has any members.
     484              :  *
     485              :  * objtype is the type of the group object, labelname is its label within
     486              :  * a containing object (if any).
     487              :  */
     488              : void
     489           20 : ExplainDummyGroup(const char *objtype, const char *labelname, ExplainState *es)
     490              : {
     491           20 :     switch (es->format)
     492              :     {
     493           20 :         case EXPLAIN_FORMAT_TEXT:
     494              :             /* nothing to do */
     495           20 :             break;
     496              : 
     497            0 :         case EXPLAIN_FORMAT_XML:
     498            0 :             ExplainXMLTag(objtype, X_CLOSE_IMMEDIATE, es);
     499            0 :             break;
     500              : 
     501            0 :         case EXPLAIN_FORMAT_JSON:
     502            0 :             ExplainJSONLineEnding(es);
     503            0 :             appendStringInfoSpaces(es->str, 2 * es->indent);
     504            0 :             if (labelname)
     505              :             {
     506            0 :                 escape_json(es->str, labelname);
     507            0 :                 appendStringInfoString(es->str, ": ");
     508              :             }
     509            0 :             escape_json(es->str, objtype);
     510            0 :             break;
     511              : 
     512            0 :         case EXPLAIN_FORMAT_YAML:
     513            0 :             ExplainYAMLLineStarting(es);
     514            0 :             if (labelname)
     515              :             {
     516            0 :                 escape_yaml(es->str, labelname);
     517            0 :                 appendStringInfoString(es->str, ": ");
     518              :             }
     519              :             else
     520              :             {
     521            0 :                 appendStringInfoString(es->str, "- ");
     522              :             }
     523            0 :             escape_yaml(es->str, objtype);
     524            0 :             break;
     525              :     }
     526           20 : }
     527              : 
     528              : /*
     529              :  * Emit the start-of-output boilerplate.
     530              :  *
     531              :  * This is just enough different from processing a subgroup that we need
     532              :  * a separate pair of subroutines.
     533              :  */
     534              : void
     535        16278 : ExplainBeginOutput(ExplainState *es)
     536              : {
     537        16278 :     switch (es->format)
     538              :     {
     539        16081 :         case EXPLAIN_FORMAT_TEXT:
     540              :             /* nothing to do */
     541        16081 :             break;
     542              : 
     543            5 :         case EXPLAIN_FORMAT_XML:
     544            5 :             appendStringInfoString(es->str,
     545              :                                    "<explain xmlns=\"http://www.postgresql.org/2009/explain\">\n");
     546            5 :             es->indent++;
     547            5 :             break;
     548              : 
     549          184 :         case EXPLAIN_FORMAT_JSON:
     550              :             /* top-level structure is an array of plans */
     551          184 :             appendStringInfoChar(es->str, '[');
     552          184 :             es->grouping_stack = lcons_int(0, es->grouping_stack);
     553          184 :             es->indent++;
     554          184 :             break;
     555              : 
     556            8 :         case EXPLAIN_FORMAT_YAML:
     557            8 :             es->grouping_stack = lcons_int(0, es->grouping_stack);
     558            8 :             break;
     559              :     }
     560        16278 : }
     561              : 
     562              : /*
     563              :  * Emit the end-of-output boilerplate.
     564              :  */
     565              : void
     566        16200 : ExplainEndOutput(ExplainState *es)
     567              : {
     568        16200 :     switch (es->format)
     569              :     {
     570        16003 :         case EXPLAIN_FORMAT_TEXT:
     571              :             /* nothing to do */
     572        16003 :             break;
     573              : 
     574            5 :         case EXPLAIN_FORMAT_XML:
     575            5 :             es->indent--;
     576            5 :             appendStringInfoString(es->str, "</explain>");
     577            5 :             break;
     578              : 
     579          184 :         case EXPLAIN_FORMAT_JSON:
     580          184 :             es->indent--;
     581          184 :             appendStringInfoString(es->str, "\n]");
     582          184 :             es->grouping_stack = list_delete_first(es->grouping_stack);
     583          184 :             break;
     584              : 
     585            8 :         case EXPLAIN_FORMAT_YAML:
     586            8 :             es->grouping_stack = list_delete_first(es->grouping_stack);
     587            8 :             break;
     588              :     }
     589        16200 : }
     590              : 
     591              : /*
     592              :  * Put an appropriate separator between multiple plans
     593              :  */
     594              : void
     595            8 : ExplainSeparatePlans(ExplainState *es)
     596              : {
     597            8 :     switch (es->format)
     598              :     {
     599            8 :         case EXPLAIN_FORMAT_TEXT:
     600              :             /* add a blank line */
     601            8 :             appendStringInfoChar(es->str, '\n');
     602            8 :             break;
     603              : 
     604            0 :         case EXPLAIN_FORMAT_XML:
     605              :         case EXPLAIN_FORMAT_JSON:
     606              :         case EXPLAIN_FORMAT_YAML:
     607              :             /* nothing to do */
     608            0 :             break;
     609              :     }
     610            8 : }
     611              : 
     612              : /*
     613              :  * Emit opening or closing XML tag.
     614              :  *
     615              :  * "flags" must contain X_OPENING, X_CLOSING, or X_CLOSE_IMMEDIATE.
     616              :  * Optionally, OR in X_NOWHITESPACE to suppress the whitespace we'd normally
     617              :  * add.
     618              :  *
     619              :  * XML restricts tag names more than our other output formats, eg they can't
     620              :  * contain white space or slashes.  Replace invalid characters with dashes,
     621              :  * so that for example "I/O Read Time" becomes "I-O-Read-Time".
     622              :  */
     623              : static void
     624          570 : ExplainXMLTag(const char *tagname, int flags, ExplainState *es)
     625              : {
     626              :     const char *s;
     627          570 :     const char *valid = "ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789-_.";
     628              : 
     629          570 :     if ((flags & X_NOWHITESPACE) == 0)
     630           66 :         appendStringInfoSpaces(es->str, 2 * es->indent);
     631          570 :     appendStringInfoCharMacro(es->str, '<');
     632          570 :     if ((flags & X_CLOSING) != 0)
     633          285 :         appendStringInfoCharMacro(es->str, '/');
     634         7896 :     for (s = tagname; *s; s++)
     635         7326 :         appendStringInfoChar(es->str, strchr(valid, *s) ? *s : '-');
     636          570 :     if ((flags & X_CLOSE_IMMEDIATE) != 0)
     637            0 :         appendStringInfoString(es->str, " /");
     638          570 :     appendStringInfoCharMacro(es->str, '>');
     639          570 :     if ((flags & X_NOWHITESPACE) == 0)
     640           66 :         appendStringInfoCharMacro(es->str, '\n');
     641          570 : }
     642              : 
     643              : /*
     644              :  * Indent a text-format line.
     645              :  *
     646              :  * We indent by two spaces per indentation level.  However, when emitting
     647              :  * data for a parallel worker there might already be data on the current line
     648              :  * (cf. ExplainOpenWorker); in that case, don't indent any more.
     649              :  */
     650              : void
     651        94388 : ExplainIndentText(ExplainState *es)
     652              : {
     653              :     Assert(es->format == EXPLAIN_FORMAT_TEXT);
     654        94388 :     if (es->str->len == 0 || es->str->data[es->str->len - 1] == '\n')
     655        94372 :         appendStringInfoSpaces(es->str, es->indent * 2);
     656        94388 : }
     657              : 
     658              : /*
     659              :  * Emit a JSON line ending.
     660              :  *
     661              :  * JSON requires a comma after each property but the last.  To facilitate this,
     662              :  * in JSON format, the text emitted for each property begins just prior to the
     663              :  * preceding line-break (and comma, if applicable).
     664              :  */
     665              : static void
     666        20893 : ExplainJSONLineEnding(ExplainState *es)
     667              : {
     668              :     Assert(es->format == EXPLAIN_FORMAT_JSON);
     669        20893 :     if (linitial_int(es->grouping_stack) != 0)
     670        19164 :         appendStringInfoChar(es->str, ',');
     671              :     else
     672         1729 :         linitial_int(es->grouping_stack) = 1;
     673        20893 :     appendStringInfoChar(es->str, '\n');
     674        20893 : }
     675              : 
     676              : /*
     677              :  * Indent a YAML line.
     678              :  *
     679              :  * YAML lines are ordinarily indented by two spaces per indentation level.
     680              :  * The text emitted for each property begins just prior to the preceding
     681              :  * line-break, except for the first property in an unlabeled group, for which
     682              :  * it begins immediately after the "- " that introduces the group.  The first
     683              :  * property of the group appears on the same line as the opening "- ".
     684              :  */
     685              : static void
     686          280 : ExplainYAMLLineStarting(ExplainState *es)
     687              : {
     688              :     Assert(es->format == EXPLAIN_FORMAT_YAML);
     689          280 :     if (linitial_int(es->grouping_stack) == 0)
     690              :     {
     691           16 :         linitial_int(es->grouping_stack) = 1;
     692              :     }
     693              :     else
     694              :     {
     695          264 :         appendStringInfoChar(es->str, '\n');
     696          264 :         appendStringInfoSpaces(es->str, es->indent * 2);
     697              :     }
     698          280 : }
     699              : 
     700              : /*
     701              :  * YAML is a superset of JSON; unfortunately, the YAML quoting rules are
     702              :  * ridiculously complicated -- as documented in sections 5.3 and 7.3.3 of
     703              :  * http://yaml.org/spec/1.2/spec.html -- so we chose to just quote everything.
     704              :  * Empty strings, strings with leading or trailing whitespace, and strings
     705              :  * containing a variety of special characters must certainly be quoted or the
     706              :  * output is invalid; and other seemingly harmless strings like "0xa" or
     707              :  * "true" must be quoted, lest they be interpreted as a hexadecimal or Boolean
     708              :  * constant rather than a string.
     709              :  */
     710              : static void
     711           28 : escape_yaml(StringInfo buf, const char *str)
     712              : {
     713           28 :     escape_json(buf, str);
     714           28 : }
        

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