Expose object name error fields in PL/pgSQL.

Specifically, permit attaching them to the error in RAISE and retrieving
them from a caught error in GET STACKED DIAGNOSTICS.  RAISE enforces
nothing about the content of the fields; for its purposes, they are just
additional string fields.  Consequently, clarify in the protocol and
libpq documentation that the usual relationships between error fields,
like a schema name appearing wherever a table name appears, are not
universal.  This freedom has other applications; consider a FDW
propagating an error from an RDBMS having no schema support.

Back-patch to 9.3, where core support for the error fields was
introduced.  This prevents the confusion of having a release where libpq
exposes the fields and PL/pgSQL does not.

Pavel Stehule, lexical revisions by Noah Misch.

Author: nmisch

doc/src/sgml/libpq.sgml

@@ -2712,9 +2712,9 @@ char *PQresultErrorField(const PGresult *res, int fieldcode);
           <term><symbol>PG_DIAG_TABLE_NAME</></term>
           <listitem>
            <para>
-            If the error was associated with a specific table, the name of
-            the table.  (When this field is present, the schema name field
-            provides the name of the table's schema.)
+            If the error was associated with a specific table, the name of the
+            table.  (Refer to the schema name field for the name of the
+            table's schema.)
            </para>
           </listitem>
          </varlistentry>
@@ -2723,9 +2723,9 @@ char *PQresultErrorField(const PGresult *res, int fieldcode);
           <term><symbol>PG_DIAG_COLUMN_NAME</></term>
           <listitem>
            <para>
-            If the error was associated with a specific table column, the
-            name of the column.  (When this field is present, the schema
-            and table name fields identify the table.)
+            If the error was associated with a specific table column, the name
+            of the column.  (Refer to the schema and table name fields to
+            identify the table.)
            </para>
           </listitem>
          </varlistentry>
@@ -2734,9 +2734,9 @@ char *PQresultErrorField(const PGresult *res, int fieldcode);
           <term><symbol>PG_DIAG_DATATYPE_NAME</></term>
           <listitem>
            <para>
-            If the error was associated with a specific data type, the name
-            of the data type.  (When this field is present, the schema name
-            field provides the name of the data type's schema.)
+            If the error was associated with a specific data type, the name of
+            the data type.  (Refer to the schema name field for the name of
+            the data type's schema.)
            </para>
           </listitem>
          </varlistentry>
@@ -2745,11 +2745,11 @@ char *PQresultErrorField(const PGresult *res, int fieldcode);
           <term><symbol>PG_DIAG_CONSTRAINT_NAME</></term>
           <listitem>
            <para>
-            If the error was associated with a specific constraint,
-            the name of the constraint.  The table or domain that the
-            constraint belongs to is reported using the fields listed
-            above.  (For this purpose, indexes are treated as constraints,
-            even if they weren't created with constraint syntax.)
+            If the error was associated with a specific constraint, the name
+            of the constraint.  Refer to fields listed above for the
+            associated table or domain.  (For this purpose, indexes are
+            treated as constraints, even if they weren't created with
+            constraint syntax.)
            </para>
           </listitem>
          </varlistentry>
@@ -2787,9 +2787,14 @@ char *PQresultErrorField(const PGresult *res, int fieldcode);
 
        <note>
         <para>
-         The fields for schema name, table name, column name, data type
-         name, and constraint name are supplied only for a limited number
-         of error types; see <xref linkend="errcodes-appendix">.
+         The fields for schema name, table name, column name, data type name,
+         and constraint name are supplied only for a limited number of error
+         types; see <xref linkend="errcodes-appendix">.  Do not assume that
+         the presence of any of these fields guarantees the presence of
+         another field.  Core error sources observe the interrelationships
+         noted above, but user-defined functions may use these fields in other
+         ways.  In the same vein, do not assume that these fields denote
+         contemporary objects in the current database.
         </para>
        </note>
 

doc/src/sgml/plpgsql.sgml

@@ -2664,11 +2664,36 @@ GET STACKED DIAGNOSTICS <replaceable>variable</replaceable> = <replaceable>item<
          <entry>text</entry>
          <entry>the SQLSTATE error code of the exception</entry>
         </row>
+        <row>
+         <entry><literal>COLUMN_NAME</literal></entry>
+         <entry>text</entry>
+         <entry>the name of column related to exception</entry>
+        </row>
+        <row>
+         <entry><literal>CONSTRAINT_NAME</literal></entry>
+         <entry>text</entry>
+         <entry>the name of constraint related to exception</entry>
+        </row>
+        <row>
+         <entry><literal>PG_DATATYPE_NAME</literal></entry>
+         <entry>text</entry>
+         <entry>the name of datatype related to exception</entry>
+        </row>
         <row>
          <entry><literal>MESSAGE_TEXT</literal></entry>
          <entry>text</entry>
          <entry>the text of the exception's primary message</entry>
         </row>
+        <row>
+         <entry><literal>TABLE_NAME</literal></entry>
+         <entry>text</entry>
+         <entry>the name of table related to exception</entry>
+        </row>
+        <row>
+         <entry><literal>SCHEMA_NAME</literal></entry>
+         <entry>text</entry>
+         <entry>the name of schema related to exception</entry>
+        </row>
         <row>
          <entry><literal>PG_EXCEPTION_DETAIL</literal></entry>
          <entry>text</entry>
@@ -3355,6 +3380,17 @@ RAISE NOTICE 'Calling cs_create_job(%)', v_job_id;
         five-character SQLSTATE code.</para>
       </listitem>
      </varlistentry>
+
+     <varlistentry>
+      <term><literal>COLUMN</literal></term>
+      <term><literal>CONSTRAINT</literal></term>
+      <term><literal>DATATYPE</literal></term>
+      <term><literal>TABLE</literal></term>
+      <term><literal>SCHEMA</literal></term>
+      <listitem>
+       <para>Supplies the name of a related object.</para>
+      </listitem>
+     </varlistentry>
     </variablelist>
    </para>
 

doc/src/sgml/protocol.sgml

@@ -4788,8 +4788,8 @@ message.
 <listitem>
 <para>
         Table name: if the error was associated with a specific table, the
-        name of the table.  (When this field is present, the schema name field
-        provides the name of the table's schema.)
+        name of the table.  (Refer to the schema name field for the name of
+        the table's schema.)
 </para>
 </listitem>
 </varlistentry>
@@ -4801,8 +4801,8 @@ message.
 <listitem>
 <para>
         Column name: if the error was associated with a specific table column,
-        the name of the column.  (When this field is present, the schema and
-        table name fields identify the table.)
+        the name of the column.  (Refer to the schema and table name fields to
+        identify the table.)
 </para>
 </listitem>
 </varlistentry>
@@ -4814,8 +4814,8 @@ message.
 <listitem>
 <para>
         Data type name: if the error was associated with a specific data type,
-        the name of the data type.  (When this field is present, the schema
-        name field provides the name of the data type's schema.)
+        the name of the data type.  (Refer to the schema name field for the
+        name of the data type's schema.)
 </para>
 </listitem>
 </varlistentry>
@@ -4827,10 +4827,10 @@ message.
 <listitem>
 <para>
         Constraint name: if the error was associated with a specific
-        constraint, the name of the constraint.  The table or domain that the
-        constraint belongs to is reported using the fields listed above.  (For
-        this purpose, indexes are treated as constraints, even if they weren't
-        created with constraint syntax.)
+        constraint, the name of the constraint.  Refer to fields listed above
+        for the associated table or domain.  (For this purpose, indexes are
+        treated as constraints, even if they weren't created with constraint
+        syntax.)
 </para>
 </listitem>
 </varlistentry>
@@ -4876,7 +4876,12 @@ message.
  <para>
   The fields for schema name, table name, column name, data type name, and
   constraint name are supplied only for a limited number of error types;
-  see <xref linkend="errcodes-appendix">.
+  see <xref linkend="errcodes-appendix">.  Frontends should not assume that
+  the presence of any of these fields guarantees the presence of another
+  field.  Core error sources observe the interrelationships noted above, but
+  user-defined functions may use these fields in other ways.  In the same
+  vein, clients should not assume that these fields denote contemporary
+  objects in the current database.
  </para>
 </note>
 

src/pl/plpgsql/src/pl_exec.c

@@ -1569,11 +1569,36 @@ exec_stmt_getdiag(PLpgSQL_execstate *estate, PLpgSQL_stmt_getdiag *stmt)
 							unpack_sql_state(estate->cur_error->sqlerrcode));
 				break;
 
+			case PLPGSQL_GETDIAG_COLUMN_NAME:
+				exec_assign_c_string(estate, var,
+									 estate->cur_error->column_name);
+				break;
+
+			case PLPGSQL_GETDIAG_CONSTRAINT_NAME:
+				exec_assign_c_string(estate, var,
+									 estate->cur_error->constraint_name);
+				break;
+
+			case PLPGSQL_GETDIAG_DATATYPE_NAME:
+				exec_assign_c_string(estate, var,
+									 estate->cur_error->datatype_name);
+				break;
+
 			case PLPGSQL_GETDIAG_MESSAGE_TEXT:
 				exec_assign_c_string(estate, var,
 									 estate->cur_error->message);
 				break;
 
+			case PLPGSQL_GETDIAG_TABLE_NAME:
+				exec_assign_c_string(estate, var,
+									 estate->cur_error->table_name);
+				break;
+
+			case PLPGSQL_GETDIAG_SCHEMA_NAME:
+				exec_assign_c_string(estate, var,
+									 estate->cur_error->schema_name);
+				break;
+
 			default:
 				elog(ERROR, "unrecognized diagnostic item kind: %d",
 					 diag_item->kind);
@@ -2799,6 +2824,16 @@ exec_init_tuple_store(PLpgSQL_execstate *estate)
 	estate->rettupdesc = rsi->expectedDesc;
 }
 
+#define SET_RAISE_OPTION_TEXT(opt, name) \
+do { \
+	if (opt) \
+		ereport(ERROR, \
+				(errcode(ERRCODE_SYNTAX_ERROR), \
+				 errmsg("RAISE option already specified: %s", \
+						name))); \
+	opt = pstrdup(extval); \
+} while (0)
+
 /* ----------
  * exec_stmt_raise			Build a message and throw it with elog()
  * ----------
@@ -2811,6 +2846,11 @@ exec_stmt_raise(PLpgSQL_execstate *estate, PLpgSQL_stmt_raise *stmt)
 	char	   *err_message = NULL;
 	char	   *err_detail = NULL;
 	char	   *err_hint = NULL;
+	char	   *err_column = NULL;
+	char	   *err_constraint = NULL;
+	char	   *err_datatype = NULL;
+	char	   *err_table = NULL;
+	char	   *err_schema = NULL;
 	ListCell   *lc;
 
 	/* RAISE with no parameters: re-throw current exception */
@@ -2927,28 +2967,28 @@ exec_stmt_raise(PLpgSQL_execstate *estate, PLpgSQL_stmt_raise *stmt)
 				condname = pstrdup(extval);
 				break;
 			case PLPGSQL_RAISEOPTION_MESSAGE:
-				if (err_message)
-					ereport(ERROR,
-							(errcode(ERRCODE_SYNTAX_ERROR),
-							 errmsg("RAISE option already specified: %s",
-									"MESSAGE")));
-				err_message = pstrdup(extval);
+				SET_RAISE_OPTION_TEXT(err_message, "MESSAGE");
 				break;
 			case PLPGSQL_RAISEOPTION_DETAIL:
-				if (err_detail)
-					ereport(ERROR,
-							(errcode(ERRCODE_SYNTAX_ERROR),
-							 errmsg("RAISE option already specified: %s",
-									"DETAIL")));
-				err_detail = pstrdup(extval);
+				SET_RAISE_OPTION_TEXT(err_detail, "DETAIL");
 				break;
 			case PLPGSQL_RAISEOPTION_HINT:
-				if (err_hint)
-					ereport(ERROR,
-							(errcode(ERRCODE_SYNTAX_ERROR),
-							 errmsg("RAISE option already specified: %s",
-									"HINT")));
-				err_hint = pstrdup(extval);
+				SET_RAISE_OPTION_TEXT(err_hint, "HINT");
+				break;
+			case PLPGSQL_RAISEOPTION_COLUMN:
+				SET_RAISE_OPTION_TEXT(err_column, "COLUMN");
+				break;
+			case PLPGSQL_RAISEOPTION_CONSTRAINT:
+				SET_RAISE_OPTION_TEXT(err_constraint, "CONSTRAINT");
+				break;
+			case PLPGSQL_RAISEOPTION_DATATYPE:
+				SET_RAISE_OPTION_TEXT(err_datatype, "DATATYPE");
+				break;
+			case PLPGSQL_RAISEOPTION_TABLE:
+				SET_RAISE_OPTION_TEXT(err_table, "TABLE");
+				break;
+			case PLPGSQL_RAISEOPTION_SCHEMA:
+				SET_RAISE_OPTION_TEXT(err_schema, "SCHEMA");
 				break;
 			default:
 				elog(ERROR, "unrecognized raise option: %d", opt->opt_type);
@@ -2982,7 +3022,17 @@ exec_stmt_raise(PLpgSQL_execstate *estate, PLpgSQL_stmt_raise *stmt)
 			(err_code ? errcode(err_code) : 0,
 			 errmsg_internal("%s", err_message),
 			 (err_detail != NULL) ? errdetail_internal("%s", err_detail) : 0,
-			 (err_hint != NULL) ? errhint("%s", err_hint) : 0));
+			 (err_hint != NULL) ? errhint("%s", err_hint) : 0,
+			 (err_column != NULL) ?
+			 err_generic_string(PG_DIAG_COLUMN_NAME, err_column) : 0,
+			 (err_constraint != NULL) ?
+			 err_generic_string(PG_DIAG_CONSTRAINT_NAME, err_constraint) : 0,
+			 (err_datatype != NULL) ?
+			 err_generic_string(PG_DIAG_DATATYPE_NAME, err_datatype) : 0,
+			 (err_table != NULL) ?
+			 err_generic_string(PG_DIAG_TABLE_NAME, err_table) : 0,
+			 (err_schema != NULL) ?
+			 err_generic_string(PG_DIAG_SCHEMA_NAME, err_schema) : 0));
 
 	estate->err_text = NULL;	/* un-suppress... */
 
@@ -2994,6 +3044,16 @@ exec_stmt_raise(PLpgSQL_execstate *estate, PLpgSQL_stmt_raise *stmt)
 		pfree(err_detail);
 	if (err_hint != NULL)
 		pfree(err_hint);
+	if (err_column != NULL)
+		pfree(err_column);
+	if (err_constraint != NULL)
+		pfree(err_constraint);
+	if (err_datatype != NULL)
+		pfree(err_datatype);
+	if (err_table != NULL)
+		pfree(err_table);
+	if (err_schema != NULL)
+		pfree(err_schema);
 
 	return PLPGSQL_RC_OK;
 }

src/pl/plpgsql/src/pl_funcs.c

@@ -285,8 +285,18 @@ plpgsql_getdiag_kindname(int kind)
 			return "PG_EXCEPTION_HINT";
 		case PLPGSQL_GETDIAG_RETURNED_SQLSTATE:
 			return "RETURNED_SQLSTATE";
+		case PLPGSQL_GETDIAG_COLUMN_NAME:
+			return "COLUMN_NAME";
+		case PLPGSQL_GETDIAG_CONSTRAINT_NAME:
+			return "CONSTRAINT_NAME";
+		case PLPGSQL_GETDIAG_DATATYPE_NAME:
+			return "PG_DATATYPE_NAME";
 		case PLPGSQL_GETDIAG_MESSAGE_TEXT:
 			return "MESSAGE_TEXT";
+		case PLPGSQL_GETDIAG_TABLE_NAME:
+			return "TABLE_NAME";
+		case PLPGSQL_GETDIAG_SCHEMA_NAME:
+			return "SCHEMA_NAME";
 	}
 
 	return "unknown";
@@ -1317,6 +1327,21 @@ dump_raise(PLpgSQL_stmt_raise *stmt)
 				case PLPGSQL_RAISEOPTION_HINT:
 					printf("    HINT = ");
 					break;
+				case PLPGSQL_RAISEOPTION_COLUMN:
+					printf("    COLUMN = ");
+					break;
+				case PLPGSQL_RAISEOPTION_CONSTRAINT:
+					printf("    CONSTRAINT = ");
+					break;
+				case PLPGSQL_RAISEOPTION_DATATYPE:
+					printf("    DATATYPE = ");
+					break;
+				case PLPGSQL_RAISEOPTION_TABLE:
+					printf("    TABLE = ");
+					break;
+				case PLPGSQL_RAISEOPTION_SCHEMA:
+					printf("    SCHEMA = ");
+					break;
 			}
 			dump_expr(opt->expr);
 			printf("\n");