If a lot of chunks are involved then the current pl/pgsql function
to compute the size of each chunk via a nested loop is pretty slow.
Additionally, the current functionality makes a system call to get the
file size on disk for each chunk everytime this function is called.
That again slows things down. We now have an approximate function which
is implemented in C to avoid the issues in the pl/pgsql function.
Additionally, this function also uses per backend caching using the
smgr layer to compute the approximate size cheaply. The PG cache
invalidation clears off the cached size for a chunk when DML happens
into it. That size cache is thus able to get the latest size in a
matter of minutes. Also, due to the backend caching, any long running
session will only fetch latest data for new or modified chunks and can
use the cached data (which is calculated afresh the first time around)
effectively for older chunks.
Make truncating a uncompressed chunk drop the data for the case where
they reside in a corresponding compressed chunk.
Generate invalidations for Continuous Aggregates after TRUNCATE, so
as to have consistent refresh operations on the materialization
hypertable.
Fixes#4362
This patch fixes a segfault when calling show_chunks on internal
compressed hypertable and a cache lookup failure for drop_chunks
when calling on internal compressed hypertable.
This patch removes enterprise license support and moves
move_chunk() function under community license (TSL).
Licensing validation code been reworked and simplified.
Previously used timescaledb.license_key guc been renamed to
timescaledb.license.
This change also makes testing code more strict against
used license. Apache test suite now can test only apache-licensed
functions.
Fixes#2359
