Support retrieval of results in chunks with libpq. This patch generalizes libpq's existing single-row mode to allow individual partial-result PGresults to contain up to N rows, rather than always one row. This reduces malloc overhead compared to plain single-row mode, and it is very useful for psql's FETCH_COUNT feature, since otherwise we'd have to add code (and cycles) to either merge single-row PGresults into a bigger one or teach psql's results-printing logic to accept arrays of PGresults.
To avoid API breakage, PQsetSingleRowMode() remains the same, and we add a new function PQsetChunkedRowsMode() to invoke the more general case. Also, PGresults obtained the old way continue to carry the PGRES_SINGLE_TUPLE status code, while if PQsetChunkedRowsMode() is used then their status code is PGRES_TUPLES_CHUNK. The underlying logic is the same either way, though. Daniel Vérité, reviewed by Laurenz Albe and myself (and whacked around a bit by me, so any remaining bugs are my fault) Discussion: https://postgr.es/m/cakzirmxsvtko928cm+-advsmyepmu3l9dqca9nwqjvlpcee...@mail.gmail.com Branch ------ master Details ------- https://git.postgresql.org/pg/commitdiff/4643a2b265e967cc5f13ffa0c7c6912dbb3466d0 Modified Files -------------- doc/src/sgml/libpq.sgml | 107 +++++++++++---- .../libpqwalreceiver/libpqwalreceiver.c | 3 +- src/bin/pg_amcheck/pg_amcheck.c | 1 + src/interfaces/libpq/exports.txt | 1 + src/interfaces/libpq/fe-exec.c | 146 +++++++++++++-------- src/interfaces/libpq/fe-protocol3.c | 3 +- src/interfaces/libpq/libpq-fe.h | 4 +- src/interfaces/libpq/libpq-int.h | 10 +- src/test/modules/libpq_pipeline/libpq_pipeline.c | 40 ++++++ .../modules/libpq_pipeline/traces/singlerow.trace | 14 ++ 10 files changed, 243 insertions(+), 86 deletions(-)
