This change is part of an effort to create a consistent way
of dealing with metadata catalog updates, which is currently
a mix of C API and INSERT/UPDATE/DELETE statements from SQL
code. This mix makes catalog handling unnecessarily complex as
there are multiple ways to update metadata, increasing the risk
of security issues with publically exposed SQL functions. It also
complicates things like cache invalidation, requiring different
mechanisms for C and SQL code. Catalog updates from SQL code
require triggers on metadata tables for cache invalidation that
do not work with native catalog updates.
The creation of chunks has been particularly messy in this regard,
making the code hard to follow. Especially the handling of a chunk's
constraints, where dimensional and other constraints were handled
differently. With this change, constraint handling is now consistent
across constraint types with a single API for updating metadata.
Reduce memory usage for out-of-order inserts
The chunk_result_relation_info should be put on the chunk memory
context. This will cause the rri constraint expr to also go onto
that context and be correctly freed when the chunk insert state
is destroyed.
This change refactors the chunk index handling to make better use
of standard PostgreSQL catalog information, while removing the
hypertable_index metadata table and associated triggers, including
those on the chunk_index table. The chunk_index table itself is
also simplified.
A benefit of this refactoring is that indexes are no longer
created using string mangling to construct the CREATE INDEX command
for a chunk, based on the string definition of the hypertable
index. Instead, indexes are created in C using proper index-related
internal data structures.
Chunk indexes can now also be renamed and are added in the parent
index tablespace. Changing tablespace on a hypertable index also
recurses to chunks, as expected. Default indexes that are added when
creating a hypertable use the hypertable's tablespace.
Creating Hypertable indexes with the CONCURRENTLY modifier is
currently blocked, due to unclear semantics regarding concurrent
creation over many tables, including how to deal with snapshots.
Streamline code and remove triggers from chunk and
chunk_constraint. Lots of additional cleanup. Also removes need to CASCADE
hypertable drops (fixes#88).
This PR add support for primary-key, foreign-key, unique, and exclusion constraints.
Previously supported are CHECK and NOT NULL constraints. Now, foreign key
constraints where a hypertable references a plain table is support
(while vice versa, with a plain table references a hypertable, is still not).
