da7a1dc0d6
Separate att_align_nominal() into two macros, similarly to what was already done with att_align_datum() and att_align_pointer(). The inner macro att_nominal_alignby() is really just TYPEALIGN(), while att_align_nominal() retains its previous API by mapping TYPALIGN_xxx values to numbers of bytes to align to and then calling att_nominal_alignby(). In support of this, split out tupdesc.c's logic to do that mapping into a publicly visible function typalign_to_alignby(). Having done that, we can replace performance-critical uses of att_align_nominal() with att_nominal_alignby(), where the typalign_to_alignby() mapping is done just once outside the loop. In most places I settled for doing typalign_to_alignby() once per function. We could in many places pass the alignby value in from the caller if we wanted to change function APIs for this purpose; but I'm a bit loath to do that, especially for exported APIs that extensions might call. Replacing a char typalign argument by a uint8 typalignby argument would be an API change that compilers would fail to warn about, thus silently breaking code in hard-to-debug ways. I did revise the APIs of array_iter_setup and array_iter_next, moving the element type attribute arguments to the former; if any external code uses those, the argument-count change will cause visible compile failures. Performance testing shows that ExecEvalScalarArrayOp is sped up by about 10% by this change, when using a simple per-element function such as int8eq. I did not check any of the other loops optimized here, but it's reasonable to expect similar gains. Although the motivation for creating this patch was to avoid a performance loss if we add some more typalign values, it evidently is worth doing whether that patch lands or not. Discussion: https://postgr.es/m/1127261.1769649624@sss.pgh.pa.us
PostgreSQL Database Management System
This directory contains the source code distribution of the PostgreSQL database management system.
PostgreSQL is an advanced object-relational database management system that supports an extended subset of the SQL standard, including transactions, foreign keys, subqueries, triggers, user-defined types and functions. This distribution also contains C language bindings.
Copyright and license information can be found in the file COPYRIGHT.
General documentation about this version of PostgreSQL can be found at https://www.postgresql.org/docs/devel/. In particular, information about building PostgreSQL from the source code can be found at https://www.postgresql.org/docs/devel/installation.html.
The latest version of this software, and related software, may be obtained at https://www.postgresql.org/download/. For more information look at our web site located at https://www.postgresql.org/.