PG17.1 Support - SQL changes, new features

[naisila]

Introduction

This issue tracks how Citus will handle PostgreSQL 17's SQL changes and new features. Resources that we used are the following:

• Official release notes

Note 1: We should finish "Features to support" and "Meaningful error messages" first, then the ones that require only testing.
Note 2: You can refer to the PRs in #7138 to understand better how we should extend our test suite. Add your name to the subtask you are working on.

Features to support in Citus

We plan to support the following new options:

• Allow specification of table access methods on partitioned tables postgres/postgres@374c7a229
  @m3hm3t
  Probably just needs adding tests.
• Supporting MEMORY option when extracting EXPLAIN output from workers. postgres/postgres@5de890e36
  @naisila
  PG17 - Propagate EXPLAIN options: MEMORY and SERIALIZE #7802
• Add EXPLAIN option SERIALIZE to report the cost of converting data for network transmission postgres/postgres@06286709e
  @naisila
  PG17 - Propagate EXPLAIN options: MEMORY and SERIALIZE #7802
• Add support for MERGE ... WHEN NOT MATCHED BY SOURCE postgres/postgres@0294df2f1
  @naisila
  PG17 - Add tests for MERGE ... WHEN NOT MATCHED BY SOURCE #7807
• Allow exclusion constraints on partitioned tables postgres/postgres@8c852ba9a
  @m3hm3t
  PG17 compatibility: Fix Test Failure in multi_alter_table_add_const #7733
• Allow partitioned tables to have identity columns postgres/postgres@699586315
  @colm-mchugh
  PG17 compatibility: account for identity columns in partitioned tables. #7785
• Add clearer ALTER INDEX/TABLE method to set a column to the default statistics target postgres/postgres@4f622503d
  @naisila
  Citus doesn't support altering the column of a distributed table for any reason. Therefore altering a table's column's statistics is not allowed by default. Citus however allows altering the statistics of a column of an index.
  Tests for ALTER INDEX ALTER COLUMN SET STATISTICS DEFAULT #7808

Meaningful error messages for currently unsupported features

For now, we will not provide support for the following, but we will print error messages with possible hints/workarounds for the user:

• Allow ALTER TABLE to change a column's generation expression postgres/postgres@5d06e99a3
• Allow the session time zone to be specified by AT LOCAL postgres/postgres@97957fdba
• Add DEFAULT setting for ALTER TABLE .. SET ACCESS METHOD postgres/postgres@d61a6cad6
  @m3hm3t
  PG17 Add Regression Test for ALTER TABLE ... SET ACCESS METHOD DEFAULT #7803
• Add new COPY option SAVE_ERROR_TO postgres/postgres@9e2d87011
  @naisila
• Add new COPY option LOG_VERBOSITY which reports COPY FROM ignored error rows postgres/postgres@f5a227895
  @naisila
• In COPY FROM, allow easy specification that all columns should be forced null or not null postgres/postgres@f6d4c9cf1
  @naisila
• Allow MERGE to modify updatable views postgres/postgres@5f2e179bd
  @tejeswarm
  Support PostgreSQL 17 MERGE features in Citus with clean exceptions #7781
• Allow MERGE to use the RETURNING clause postgres/postgres@c649fa24a
  @tejeswarm
  Support PostgreSQL 17 MERGE features in Citus with clean exceptions #7781

Add regression tests or just test locally

Most of PG17's new additions simply work with Citus. However, we add tests for some of them to ensure consistency and maintainability for the future. For some other additions, testing locally is sufficient.

• Add event trigger support for REINDEX postgres/postgres@f21848de2
• New SQL/JSON capabilities JSON_TABLE(), JSON(), JSON_SCALAR(), and JSON_SERIALIZE(), JSON_EXISTS(), JSON_QUERY(), and JSON_VALUE(), jsonpath methods
• Allow COPY FROM to report the number of skipped rows during processing postgres/postgres@729439607
• New client-side connection option, sslnegotiation=direct postgres/postgres@d39a49c1e
• Allow the grouping of file system reads with the new system variable io_combine_limit postgres/postgres@210622c60
• Add system variable allow_alter_system to disallow ALTER SYSTEM postgres/postgres@d3ae2a24f
• Add logical replication failover control to CREATE/ALTER SUBSCRIPTION postgres/postgres@776621a5e
• Allow parenthesized syntax for CLUSTER options if a table name is not specified postgres/postgres@cdaedfc96
• Add support for event triggers that fire at connection time postgres/postgres@e83d1b0c4
• Allow the interval data type to support +/-infinity values postgres/postgres@519fc1bd9
• Allow the use of an ENUM added via ALTER TYPE if the type was created in the same transaction postgres/postgres@af1d39584
• to_timestamp(), uuid_extract_timestamp() , uuid_extract_version() , random(min, max) , to_bin(), to_oct(), unicode_version(), icu_unicode_version(), xmltext() , to_regtypemod(), pg_basetype(), pg_column_toast_chunk_id()