perf(postgresql): add INSERT batch mode: values & unnest

[tin-thebc]

• Load nullability and defaults from pg_catalog
• Extend ColumnInfo with nullable, hasDefault, defaultExpr
• Inline defaults in UNNEST projections (scalars and arrays)
• Refuse UNNEST when NOT NULL without default is absent
• Improve batching logs; set default batch size to 50
• Update PRD task 11c with implementation details

[maoueh]

@tin-thebc This is a follow up of #105 correct?

[tin-thebc]

@maoueh yes that's correct, can you help me to close the duplicate one?

[GabrielCartier]

Hi @tin-thebc — thanks for this, and sorry it sat so long.

This repository is being deprecated (see #133). The SQL sink now lives in the main substreams CLI as substreams sink postgres / substreams sink clickhouse, shipped in substreams v1.20.2. All future work happens there, so this PR can't land here.

The code moved wholesale, so the port is mostly a path rewrite:

here	substreams repo
db_changes/db/	sink/sql/db_changes/db/
db_changes/sinker/	sink/sql/db_changes/sinker/
cmd/substreams-sink-sql/run.go	cmd/substreams/sink_postgres.go

The batch/unnest work isn't in the CLI yet, and we'd still like it — would you be up for reopening it against streamingfast/substreams (branch off develop)? The branch conflicts here anyway, so rebasing onto the new tree is roughly the same effort. If you'd rather not redo it, say so and we'll port it ourselves with credit to you.

Closing this one out. (#105, the earlier duplicate, is already closed.)