Re: CREATE TABLE AS WITH NO DATA - Mailing list pgsql-hackers

From Tom Lane
Subject Re: CREATE TABLE AS WITH NO DATA
Date
Msg-id 11076.1225155122@sss.pgh.pa.us
Whole thread Raw
In response to Re: CREATE TABLE AS WITH NO DATA  (Tom Lane <tgl@sss.pgh.pa.us>)
List pgsql-hackers
I wrote:
> I'd like us to be trying to get rid of the special cases in base_yylex
> not add more.  (It strikes me that now that WITH is fully reserved,
> we might not need some of the ones that are there anymore.)

In fact, it looks like what we should do is heed the existing comment
in parser.c: remove the existing WITH_foo combined tokens and invent
WITH_TIME instead.  Then, no additional combined tokens are needed to
handle WITH [NO] DATA.  So I propose the attached form of the patch
instead (docs omitted).

            regards, tom lane

Index: src/backend/parser/gram.y
===================================================================
RCS file: /cvsroot/pgsql/src/backend/parser/gram.y,v
retrieving revision 2.630
diff -c -r2.630 gram.y
*** src/backend/parser/gram.y    27 Oct 2008 09:37:47 -0000    2.630
--- src/backend/parser/gram.y    28 Oct 2008 00:46:25 -0000
***************
*** 216,222 ****
  %type <ival>    opt_lock lock_type cast_context
  %type <boolean>    opt_force opt_or_replace
                  opt_grant_grant_option opt_grant_admin_option
!                 opt_nowait opt_if_exists

  %type <list>    OptRoleList
  %type <defelt>    OptRoleElem
--- 216,222 ----
  %type <ival>    opt_lock lock_type cast_context
  %type <boolean>    opt_force opt_or_replace
                  opt_grant_grant_option opt_grant_admin_option
!                 opt_nowait opt_if_exists opt_with_data

  %type <list>    OptRoleList
  %type <defelt>    OptRoleElem
***************
*** 485,491 ****
   * list and so can never be entered directly.  The filter in parser.c
   * creates these tokens when required.
   */
! %token            NULLS_FIRST NULLS_LAST WITH_CASCADED WITH_LOCAL WITH_CHECK

  /* Special token types, not actually keywords - see the "lex" file */
  %token <str>    IDENT FCONST SCONST BCONST XCONST Op
--- 485,491 ----
   * list and so can never be entered directly.  The filter in parser.c
   * creates these tokens when required.
   */
! %token            NULLS_FIRST NULLS_LAST WITH_TIME

  /* Special token types, not actually keywords - see the "lex" file */
  %token <str>    IDENT FCONST SCONST BCONST XCONST Op
***************
*** 2416,2422 ****
   */

  CreateAsStmt:
!         CREATE OptTemp TABLE create_as_target AS SelectStmt
                  {
                      /*
                       * When the SelectStmt is a set-operation tree, we must
--- 2416,2422 ----
   */

  CreateAsStmt:
!         CREATE OptTemp TABLE create_as_target AS SelectStmt opt_with_data
                  {
                      /*
                       * When the SelectStmt is a set-operation tree, we must
***************
*** 2433,2438 ****
--- 2433,2441 ----
                                   scanner_errposition(exprLocation((Node *) n->intoClause))));
                      $4->rel->istemp = $2;
                      n->intoClause = $4;
+                     /* Implement WITH NO DATA by forcing top-level LIMIT 0 */
+                     if (!$7)
+                         ((SelectStmt *) $6)->limitCount = makeIntConst(0, -1);
                      $$ = $6;
                  }
          ;
***************
*** 2475,2480 ****
--- 2478,2489 ----
                  }
          ;

+ opt_with_data:
+             WITH DATA_P                                { $$ = TRUE; }
+             | WITH NO DATA_P                        { $$ = FALSE; }
+             | /*EMPTY*/                                { $$ = TRUE; }
+         ;
+

  /*****************************************************************************
   *
***************
*** 5387,5410 ****
                  }
          ;

- /*
-  * We use merged tokens here to avoid creating shift/reduce conflicts against
-  * a whole lot of other uses of WITH.
-  */
  opt_check_option:
!         WITH_CHECK OPTION
                  {
                      ereport(ERROR,
                              (errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
                               errmsg("WITH CHECK OPTION is not implemented")));
                  }
!         | WITH_CASCADED CHECK OPTION
                  {
                      ereport(ERROR,
                              (errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
                               errmsg("WITH CHECK OPTION is not implemented")));
                  }
!         | WITH_LOCAL CHECK OPTION
                  {
                      ereport(ERROR,
                              (errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
--- 5396,5415 ----
                  }
          ;

  opt_check_option:
!         WITH CHECK OPTION
                  {
                      ereport(ERROR,
                              (errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
                               errmsg("WITH CHECK OPTION is not implemented")));
                  }
!         | WITH CASCADED CHECK OPTION
                  {
                      ereport(ERROR,
                              (errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
                               errmsg("WITH CHECK OPTION is not implemented")));
                  }
!         | WITH LOCAL CHECK OPTION
                  {
                      ereport(ERROR,
                              (errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
***************
*** 7509,7515 ****
          ;

  opt_timezone:
!             WITH TIME ZONE                            { $$ = TRUE; }
              | WITHOUT TIME ZONE                        { $$ = FALSE; }
              | /*EMPTY*/                                { $$ = FALSE; }
          ;
--- 7514,7520 ----
          ;

  opt_timezone:
!             WITH_TIME ZONE                            { $$ = TRUE; }
              | WITHOUT TIME ZONE                        { $$ = FALSE; }
              | /*EMPTY*/                                { $$ = FALSE; }
          ;
Index: src/backend/parser/parser.c
===================================================================
RCS file: /cvsroot/pgsql/src/backend/parser/parser.c,v
retrieving revision 1.74
diff -c -r1.74 parser.c
*** src/backend/parser/parser.c    29 Aug 2008 13:02:32 -0000    1.74
--- src/backend/parser/parser.c    28 Oct 2008 00:46:25 -0000
***************
*** 129,156 ****
          case WITH:

              /*
!              * WITH CASCADED, LOCAL, or CHECK must be reduced to one token
!              *
!              * XXX an alternative way is to recognize just WITH_TIME and put
!              * the ugliness into the datetime datatype productions instead of
!              * WITH CHECK OPTION.  However that requires promoting WITH to a
!              * fully reserved word.  If we ever have to do that anyway
!              * (perhaps for SQL99 recursive queries), come back and simplify
!              * this code.
               */
              cur_yylval = base_yylval;
              cur_yylloc = base_yylloc;
              next_token = base_yylex();
              switch (next_token)
              {
!                 case CASCADED:
!                     cur_token = WITH_CASCADED;
!                     break;
!                 case LOCAL:
!                     cur_token = WITH_LOCAL;
!                     break;
!                 case CHECK:
!                     cur_token = WITH_CHECK;
                      break;
                  default:
                      /* save the lookahead token for next time */
--- 129,143 ----
          case WITH:

              /*
!              * WITH TIME must be reduced to one token
               */
              cur_yylval = base_yylval;
              cur_yylloc = base_yylloc;
              next_token = base_yylex();
              switch (next_token)
              {
!                 case TIME:
!                     cur_token = WITH_TIME;
                      break;
                  default:
                      /* save the lookahead token for next time */
Index: src/interfaces/ecpg/preproc/parser.c
===================================================================
RCS file: /cvsroot/pgsql/src/interfaces/ecpg/preproc/parser.c,v
retrieving revision 1.3
diff -c -r1.3 parser.c
*** src/interfaces/ecpg/preproc/parser.c    1 Jan 2008 19:45:59 -0000    1.3
--- src/interfaces/ecpg/preproc/parser.c    28 Oct 2008 00:46:25 -0000
***************
*** 98,125 ****
          case WITH:

              /*
!              * WITH CASCADED, LOCAL, or CHECK must be reduced to one token
!              *
!              * XXX an alternative way is to recognize just WITH_TIME and put
!              * the ugliness into the datetime datatype productions instead of
!              * WITH CHECK OPTION.  However that requires promoting WITH to a
!              * fully reserved word.  If we ever have to do that anyway
!              * (perhaps for SQL99 recursive queries), come back and simplify
!              * this code.
               */
              cur_yylval = base_yylval;
              cur_yylloc = base_yylloc;
              next_token = base_yylex();
              switch (next_token)
              {
!                 case CASCADED:
!                     cur_token = WITH_CASCADED;
!                     break;
!                 case LOCAL:
!                     cur_token = WITH_LOCAL;
!                     break;
!                 case CHECK:
!                     cur_token = WITH_CHECK;
                      break;
                  default:
                      /* save the lookahead token for next time */
--- 98,112 ----
          case WITH:

              /*
!              * WITH TIME must be reduced to one token
               */
              cur_yylval = base_yylval;
              cur_yylloc = base_yylloc;
              next_token = base_yylex();
              switch (next_token)
              {
!                 case TIME:
!                     cur_token = WITH_TIME;
                      break;
                  default:
                      /* save the lookahead token for next time */
Index: src/interfaces/ecpg/preproc/preproc.y
===================================================================
RCS file: /cvsroot/pgsql/src/interfaces/ecpg/preproc/preproc.y,v
retrieving revision 1.378
diff -c -r1.378 preproc.y
*** src/interfaces/ecpg/preproc/preproc.y    27 Oct 2008 09:37:47 -0000    1.378
--- src/interfaces/ecpg/preproc/preproc.y    28 Oct 2008 00:46:25 -0000
***************
*** 505,511 ****
   * list and so can never be entered directly.  The filter in parser.c
   * creates these tokens when required.
   */
! %token           NULLS_FIRST NULLS_LAST WITH_CASCADED WITH_LOCAL WITH_CHECK

  /* Special token types, not actually keywords - see the "lex" file */
  %token <str>    IDENT SCONST Op CSTRING CVARIABLE CPP_LINE IP BCONST
--- 505,511 ----
   * list and so can never be entered directly.  The filter in parser.c
   * creates these tokens when required.
   */
! %token           NULLS_FIRST NULLS_LAST WITH_TIME

  /* Special token types, not actually keywords - see the "lex" file */
  %token <str>    IDENT SCONST Op CSTRING CVARIABLE CPP_LINE IP BCONST
***************
*** 3100,3121 ****
              { $$ = cat_str(8, make_str("create or replace"), $4, make_str("view"), $6, $7, make_str("as"), $9, $10);
}
          ;

- /*
-  * We use merged tokens here to avoid creating shift/reduce conflicts against
-  * a whole lot of other uses of WITH.
-  */
  opt_check_option:
!                    WITH_CHECK OPTION
             {
                 mmerror(PARSE_ERROR, ET_ERROR, "WITH CHECK OPTION not implemented");
              $$ = EMPTY;
             }
!                    | WITH_CASCADED CHECK OPTION
             {
                 mmerror(PARSE_ERROR, ET_ERROR, "WITH CHECK OPTION not implemented");
              $$ = EMPTY;
             }
!            | WITH_LOCAL CHECK OPTION
             {
                 mmerror(PARSE_ERROR, ET_ERROR, "WITH CHECK OPTION not implemented");
              $$ = EMPTY;
--- 3100,3117 ----
              { $$ = cat_str(8, make_str("create or replace"), $4, make_str("view"), $6, $7, make_str("as"), $9, $10);
}
          ;

  opt_check_option:
!                    WITH CHECK OPTION
             {
                 mmerror(PARSE_ERROR, ET_ERROR, "WITH CHECK OPTION not implemented");
              $$ = EMPTY;
             }
!                    | WITH CASCADED CHECK OPTION
             {
                 mmerror(PARSE_ERROR, ET_ERROR, "WITH CHECK OPTION not implemented");
              $$ = EMPTY;
             }
!            | WITH LOCAL CHECK OPTION
             {
                 mmerror(PARSE_ERROR, ET_ERROR, "WITH CHECK OPTION not implemented");
              $$ = EMPTY;
***************
*** 4155,4161 ****
              { $$ = make_str("interval"); }
          ;

! opt_timezone:  WITH TIME ZONE
              { $$ = make_str("with time zone"); }
          | WITHOUT TIME ZONE
              { $$ = make_str("without time zone"); }
--- 4151,4157 ----
              { $$ = make_str("interval"); }
          ;

! opt_timezone:  WITH_TIME ZONE
              { $$ = make_str("with time zone"); }
          | WITHOUT TIME ZONE
              { $$ = make_str("without time zone"); }

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