Hashed crosstab was dying with an SPI_finish error when the source SQL

produced no rows. Now it returns 0 rows instead. Adjusted regression
test for this case.

diff --git a/contrib/tablefunc/expected/tablefunc.out b/contrib/tablefunc/expected/tablefunc.out
index 281de5d..d8f4c30 100644 (file)
--- a/contrib/tablefunc/expected/tablefunc.out
+++ b/contrib/tablefunc/expected/tablefunc.out
@@ -127,7 +127,7 @@ SELECT * FROM crosstab('SELECT rowid, attribute, val FROM ct where rowclass = ''
 -- hash based crosstab
 --
 create table cth(id serial, rowid text, rowdt timestamp, attribute text, val text);
-NOTICE:  CREATE TABLE will create implicit sequence "cth_id_seq" for "serial" column "cth.id"
+NOTICE:  CREATE TABLE will create implicit sequence "cth_id_seq" for serial column "cth.id"
 insert into cth values(DEFAULT,'test1','01 March 2003','temperature','42');
 insert into cth values(DEFAULT,'test1','01 March 2003','test_result','PASS');
 -- the next line is intentionally left commented and is therefore a "missing" attribute
@@ -193,6 +193,24 @@ SELECT * FROM crosstab(
   'SELECT DISTINCT rowdt, attribute FROM cth ORDER BY 2')
 AS c(rowid text, rowdt timestamp, temperature int4, test_result text, test_startdate timestamp, volts float8);
 ERROR:  provided "categories" SQL must return 1 column of at least one row
+-- if source query returns zero rows, get zero rows returned
+SELECT * FROM crosstab(
+  'SELECT rowid, rowdt, attribute, val FROM cth WHERE false ORDER BY 1',
+  'SELECT DISTINCT attribute FROM cth ORDER BY 1')
+AS c(rowid text, rowdt timestamp, temperature text, test_result text, test_startdate text, volts text);
+ rowid | rowdt | temperature | test_result | test_startdate | volts 
+-------+-------+-------------+-------------+----------------+-------
+(0 rows)
+
+-- if source query returns zero rows, get zero rows returned even if category query generates no rows
+SELECT * FROM crosstab(
+  'SELECT rowid, rowdt, attribute, val FROM cth WHERE false ORDER BY 1',
+  'SELECT DISTINCT attribute FROM cth WHERE false ORDER BY 1')
+AS c(rowid text, rowdt timestamp, temperature text, test_result text, test_startdate text, volts text);
+ rowid | rowdt | temperature | test_result | test_startdate | volts 
+-------+-------+-------------+-------------+----------------+-------
+(0 rows)
+
 --
 -- connectby
 --

diff --git a/contrib/tablefunc/sql/tablefunc.sql b/contrib/tablefunc/sql/tablefunc.sql
index 5292fc2..c464acb 100644 (file)
--- a/contrib/tablefunc/sql/tablefunc.sql
+++ b/contrib/tablefunc/sql/tablefunc.sql
@@ -88,6 +88,17 @@ SELECT * FROM crosstab(
   'SELECT DISTINCT rowdt, attribute FROM cth ORDER BY 2')
 AS c(rowid text, rowdt timestamp, temperature int4, test_result text, test_startdate timestamp, volts float8);
 
+-- if source query returns zero rows, get zero rows returned
+SELECT * FROM crosstab(
+  'SELECT rowid, rowdt, attribute, val FROM cth WHERE false ORDER BY 1',
+  'SELECT DISTINCT attribute FROM cth ORDER BY 1')
+AS c(rowid text, rowdt timestamp, temperature text, test_result text, test_startdate text, volts text);
+
+-- if source query returns zero rows, get zero rows returned even if category query generates no rows
+SELECT * FROM crosstab(
+  'SELECT rowid, rowdt, attribute, val FROM cth WHERE false ORDER BY 1',
+  'SELECT DISTINCT attribute FROM cth WHERE false ORDER BY 1')
+AS c(rowid text, rowdt timestamp, temperature text, test_result text, test_startdate text, volts text);
 
 --
 -- connectby

diff --git a/contrib/tablefunc/tablefunc.c b/contrib/tablefunc/tablefunc.c
index 3eccebf..f14c396 100644 (file)
--- a/contrib/tablefunc/tablefunc.c
+++ b/contrib/tablefunc/tablefunc.c
@@ -821,15 +821,6 @@ load_categories_hash(char *cats_sql, MemoryContext per_query_ctx)
                        MemoryContextSwitchTo(SPIcontext);
                }
        }
-       else
-       {
-               /* no qualifying tuples */
-               SPI_finish();
-               ereport(ERROR,
-                               (errcode(ERRCODE_SYNTAX_ERROR),
-                                errmsg("provided \"categories\" SQL must " \
-                                               "return 1 column of at least one row")));
-       }
 
        if (SPI_finish() != SPI_OK_FINISH)
                /* internal error */
@@ -879,6 +870,15 @@ get_crosstab_tuplestore(char *sql,
                                        j;
                int                     result_ncols;
 
+               if (num_categories == 0)
+               {
+                       /* no qualifying category tuples */
+                       ereport(ERROR,
+                                       (errcode(ERRCODE_SYNTAX_ERROR),
+                                       errmsg("provided \"categories\" SQL must " \
+                                                       "return 1 column of at least one row")));
+               }
+
                /*
                 * The provided SQL query must always return at least three
                 * columns:
@@ -994,11 +994,6 @@ get_crosstab_tuplestore(char *sql,
                MemoryContextSwitchTo(SPIcontext);
 
        }
-       else
-       {
-               /* no qualifying tuples */
-               SPI_finish();
-       }
 
        if (SPI_finish() != SPI_OK_FINISH)
                /* internal error */