On Wed, 23 Jul 2025 at 14:07, Peter Smith <smithpb2...@gmail.com> wrote: > On Tue, Jul 22, 2025 at 8:12 PM Japin Li <japi...@hotmail.com> wrote: > ... >> 1. >> I encountered another crash while checking VCI's internal relations. >> >> rm -rf demo >> initdb -D demo >> cat <<EOF >demo/postgresql.auto.conf >> shared_preload_libraries = 'vci' >> max_worker_processes = '20' >> EOF >> >> pg_ctl -D demo start >> >> cat <<EOF | psql postgres >> CREATE EXTENSION vci; >> CREATE TABLE t (id int, info text); >> CREATE INDEX ON t USING vci (id); >> SELECT relname FROM pg_class WHERE relname ~ '^vci_*' LIMIT 1 \gset >> SELECT * FROM :relname; >> \d+ :relname >> REFRESH MATERIALIZED VIEW :relname; >> EOF >> >> VCI's definition of internal relations as materialized views lacks the >> corresponding view bodies. >> >> + /* >> + * @see >> + * https://www.postgresql.jp/document/9.4/html/catalog-pg-rewrite.html >> + */ >> + new_rel_reltup->relhasrules = true; >> + >> + new_rel->rd_att->tdtypeid = new_type_oid; >> + >> + InsertPgClassTuple(pg_class, new_rel, new_oid, (Datum) 0, (Datum) 0); >> >> Given that VCI's internal relations are materialized views, are VCI workers >> responsible for their periodic refreshment? >> >> Or is it by design that users are unable to read the internal relations? >> > > IIUC, those VCI internal relations (implemented as materialized views) > are entirely managed by VCI logic. Users are not required to be aware > of them, and they definitely are not meant to tamper with them. >
Thanks for your explanation! > The REFRESH that you attempted should have caused a more graceful error, like: > ERROR: extension "vci" prohibits this operation on view > "vci_0000016482_00000_d" > So, thanks for reporting that the ERROR failed. Investigating... I'm considering storing this metadata in heap tables, as Citus Columnar [1] and TimescaleDB [2] also utilize them for some metadata. Is this a sound approach? I'm wondering if this is a suitable strategy for VCI? [1] https://github.com/citusdata/citus/blob/main/src/backend/columnar/columnar_metadata.c#L174 [2] https://github.com/timescale/timescaledb/blob/main/src/chunk.c#L151 -- Regards, Japin Li
