Split CREATE STATISTICS error reasons out into errdetails

Some errmsgs in statscmds.c were phrased as "...cannot be used
because...". Put the reasons into errdetails. While at it, switch
from passive voice to "cannot create..." for the errmsg.

Author: Yugo Nagata <nagata@sraoss.co.jp>
Suggested-by: John Naylor <johncnaylorls@gmail.com>
Discussion: https://postgr.es/m/CANWCAZaZeX0omWNh_ZbD_JVujzYQdRUW8UZOQ4dWh9Sg7OcAow@mail.gmail.com

diff --git a/src/backend/commands/statscmds.c b/src/backend/commands/statscmds.c
index eea45106a3ffeaf42ae38b1bef6cf4a05f445aa0..b354723be4435774bf0cdef1923eb36ef0a0ddc6 100644 (file)
--- a/src/backend/commands/statscmds.c
+++ b/src/backend/commands/statscmds.c
@@ -280,8 +280,10 @@ CreateStatistics(CreateStatsStmt *stmt, bool check_rights)
                                if (type->lt_opr == InvalidOid)
                                        ereport(ERROR,
                                                        (errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
-                                                        errmsg("column \"%s\" cannot be used in multivariate statistics because its type %s has no default btree operator class",
-                                                                       attname, format_type_be(attForm->atttypid))));
+                                                        errmsg("cannot create multivariate statistics on column \"%s\"",
+                                                                       attname),
+                                                        errdetail("The type %s has no default btree operator class.",
+                                                                          format_type_be(attForm->atttypid))));
                        }
 
                        /* Treat virtual generated columns as expressions */
@@ -325,8 +327,10 @@ CreateStatistics(CreateStatsStmt *stmt, bool check_rights)
                                if (type->lt_opr == InvalidOid)
                                        ereport(ERROR,
                                                        (errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
-                                                        errmsg("column \"%s\" cannot be used in multivariate statistics because its type %s has no default btree operator class",
-                                                                       get_attname(relid, var->varattno, false), format_type_be(var->vartype))));
+                                                        errmsg("cannot create multivariate statistics on column \"%s\"",
+                                                                       get_attname(relid, var->varattno, false)),
+                                                        errdetail("The type %s has no default btree operator class.",
+                                                                          format_type_be(var->vartype))));
                        }
 
                        /* Treat virtual generated columns as expressions */
@@ -375,8 +379,9 @@ CreateStatistics(CreateStatsStmt *stmt, bool check_rights)
                                if (type->lt_opr == InvalidOid)
                                        ereport(ERROR,
                                                        (errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
-                                                        errmsg("expression cannot be used in multivariate statistics because its type %s has no default btree operator class",
-                                                                       format_type_be(atttype))));
+                                                        errmsg("cannot create multivariate statistics on this expression"),
+                                                        errdetail("The type %s has no default btree operator class.",
+                                                                          format_type_be(atttype))));
                        }
 
                        stxexprs = lappend(stxexprs, expr);

diff --git a/src/test/regress/expected/stats_ext.out b/src/test/regress/expected/stats_ext.out
index c6ba2479413c8e68d59a273d96394b57a8e02394..37070c1a896394a1575248e10805d4c5038d26d9 100644 (file)
--- a/src/test/regress/expected/stats_ext.out
+++ b/src/test/regress/expected/stats_ext.out
@@ -99,7 +99,8 @@ CREATE STATISTICS tst (ndistinct) ON (y + z) FROM ext_stats_test;
 ERROR:  cannot specify statistics kinds when building univariate statistics
 -- multivariate statistics without a less-than operator not supported
 CREATE STATISTICS tst (ndistinct) ON x, w from ext_stats_test;
-ERROR:  column "w" cannot be used in multivariate statistics because its type xid has no default btree operator class
+ERROR:  cannot create multivariate statistics on column "w"
+DETAIL:  The type xid has no default btree operator class.
 DROP TABLE ext_stats_test;
 -- Ensure stats are dropped sanely, and test IF NOT EXISTS while at it
 CREATE TABLE ab1 (a INTEGER, b INTEGER, c INTEGER);