TRY_CONVERT

GNUmakefile.in

@@ -74,6 +74,7 @@ install:
 	$(MAKE) -C contrib/btree_gin $@
 	$(MAKE) -C contrib/pg_trgm $@
 	$(MAKE) -C contrib/tablefunc $@
+	$(MAKE) -C contrib/try_convert all
 	$(MAKE) -C contrib/passwordcheck $@
 	$(MAKE) -C contrib/pg_buffercache $@
 ifeq ($(enable_pax), yes)

contrib/Makefile

@@ -50,6 +50,7 @@ SUBDIRS = \
 		tablefunc	\
 		tcn		\
 		test_decoding	\
+		try_convert \
 		tsm_system_rows \
 		tsm_system_time \
 		unaccent	\

contrib/try_convert/.gitignore

@@ -0,0 +1,6 @@
+# Generated subdirectories
+/results/
+/sql/
+/expected/
+/input/
+/output/

contrib/try_convert/Makefile

@@ -0,0 +1,49 @@
+# contrib/try_convert/Makefile
+
+# Licensed to the Apache Software Foundation (ASF) under one
+# or more contributor license agreements.  See the NOTICE file
+# distributed with this work for additional information
+# regarding copyright ownership.  The ASF licenses this file
+# to you under the Apache License, Version 2.0 (the
+# "License"); you may not use this file except in compliance
+# with the License.  You may obtain a copy of the License at
+#
+#   http://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing,
+# software distributed under the License is distributed on an
+# "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
+# KIND, either express or implied.  See the License for the
+# specific language governing permissions and limitations
+# under the License.
+
+MODULE_big	= try_convert
+OBJS		= try_convert.o $(WIN32RES)
+
+EXTENSION = try_convert
+DATA = try_convert--1.0.sql
+PGFILEDESC = "try_convert - function for type cast"
+REGRESS = try_convert
+
+ifdef USE_PGXS
+PG_CONFIG = pg_config
+PGXS := $(shell $(PG_CONFIG) --pgxs)
+include $(PGXS)
+else
+subdir = contrib/try_convert
+top_builddir = ../..
+include $(top_builddir)/src/Makefile.global
+include $(top_srcdir)/contrib/contrib-global.mk
+endif
+
+.PHONY: generate-tests
+generate-tests:
+	mkdir -p input
+	mkdir -p output
+	python3 scripts/generate_test.py
+
+all: generate-tests
+
+.PHONY: verify
+verify:
+	python3 scripts/verify.py

contrib/try_convert/README.md

@@ -0,0 +1,92 @@
+# TRY_CONVERT
+
+TRY_CONVERT is Greenplum extension, which adds function for error-safe type cast like [TRY_CAST from SQL-Server](https://learn.microsoft.com/ru-ru/sql/t-sql/functions/try-cast-transact-sql?view=sql-server-ver16)
+
+## Usage
+
+```
+TRY_CONVERT(SOURCE_VALUE, DEFAULT_VALUE::TARGET_TYPE) 
+    returns (VALUE_IN_TARGET_TYPE or DEFAULT_VALUE)
+```
+
+```
+TRY_CONVERT('42'::text, NULL::int2) -- returns 42::int2
+TRY_CONVERT('42d'::text, NULL::int2) -- returns NULL::int2
+TRY_CONVERT('42d'::text, 1234::int2) -- returns 1234::int2
+```
+
+### Extension's type casts
+
+Casting from extensions types is able only for extensions:
+
+- hstore
+- citext
+
+To enable casting from hstore and citext types use, `add_type_for_try_convert(regtype)` function
+
+## Error handling
+
+To handle errors from type cast we use "soft" error handling concept, introduced Postgres 17 (https://github.com/postgres/postgres/commit/ccff2d20ed9622815df2a7deffce8a7b14830965), that concept we spreaded on data types in [21be368
+Preview](https://github.com/open-gpdb/gpdb/commit/21be3688729ec4468ffd083da197721860fa2cbd) and [d31f362
+](https://github.com/open-gpdb/gpdb/commit/d31f362250105e456961c2c9249693e42e67eca9) commits.
+
+## Why signature is so strange?
+
+Greenplum function polymorphism accept to have polymorphic functions only one any type in signature.  
+
+## Supported casts
+
+    ✅ Values Cast
+    ✅ Types with typemod
+    ❌ Array-Array Cast
+    ❌ To Domain type cast
+
+## Benchmark results by pgbench
+
+
+|     | without errors | with errors |
+| --- | --- | --- |
+| cast | 299.346 | ❌ fails |
+| try_convert | 984.280 | 1004.524 |
+| sql | 1384.784 | 5787.115 |
+| sql execute | 5843.220 | 5898.813 |
+
+
+SQL version:
+```
+CREATE OR REPLACE FUNCTION try_convert_into_int(_in text, d int2) RETURNS int2
+  LANGUAGE plpgsql AS
+$func$
+    BEGIN
+        RETURN CAST(_in AS int2);
+        EXCEPTION WHEN others THEN
+        RETURN d;
+    END
+$func$;
+```
+
+
+SQL with execute version:
+```
+CREATE OR REPLACE FUNCTION try_convert_by_sql(_in text, INOUT _out ANYELEMENT)
+  LANGUAGE plpgsql AS
+$func$
+BEGIN
+   EXECUTE format('SELECT %L::%s', $1, pg_typeof(_out))
+   INTO  _out;
+EXCEPTION WHEN others THEN
+   -- do nothing: _out already carries default
+END
+$func$;
+```
+
+Data:
+```
+drop table if exists text_ints; create table text_ints (n text);
+Insert into text_ints(n) select (random()*1000)::int4::text from generate_series(1,1000000);
+
+drop table if exists text_error_ints; create table text_error_ints (n text);
+Insert into text_error_ints(n) select (random()*1000000)::int8::text from generate_series(1,1000000);
+```
+
+

contrib/try_convert/data/corr_date.data

@@ -0,0 +1,40 @@
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+-13:35:45
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+12:52:43 AM
+15:52:43 AM
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+12:52:143 AM
+12:52:43 PM
+15:52:43 PM
+12:152:43 PM
+12:52:143 PM
+
+21:52:07 JST
+21:52:07 MSSSSSK
+
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+
+1982-06-27
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+1982-32-27
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+
+11-30-0002 BC
+11-30-200000000 BC

contrib/try_convert/data/corr_float4.data

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contrib/try_convert/data/corr_float8.data

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contrib/try_convert/data/corr_int2.data

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contrib/try_convert/data/corr_int4.data

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contrib/try_convert/data/corr_int8.data

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contrib/try_convert/data/corr_json.data

@@ -0,0 +1,18 @@
+{
+
+[
+{"world":"CC", "query":"AA", "line":14, "disabled":false, "date":"CAC", "coauthors":"AB"}
+{"world":"CCquery":"AA"}
+{,,,,,,}
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+{"world":"CC", "query"::"AA", "line":14, "disabled":false, "date":"CAC", "coauthors":"AB"}
+
+{"world"}
+{"world":"CC", "query":["AA":"BB", "sds"], "line":14, "disabled":false, "date":"CAC", "coauthors":"AB"}
+}}}}}}}}
+[[[[[[]]]]]]
+{[]}
+[{}]
+][][][][][][]
+{}}{}{}}}{{{}{}{}{}}}}
+kfgbidsfgadgbdfiugbhdiug

contrib/try_convert/data/corr_numeric.data

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contrib/try_convert/data/corr_time.data

@@ -0,0 +1,32 @@
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+13:-35:45
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+12:52:43 PM
+15:52:43 PM
+12:152:43 PM
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+
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+21:52:07 MSSSSSK
+
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+
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+1982-06-32 18:52:43
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