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Here we convert CompactAttribute.attalign from a char, which is directly derived from pg_attribute.attalign into a uint8, which stores the number of bytes to align the column's value by in the tuple. This allows tuple deformation and tuple size calculations to move away from using the inefficient att_align_nominal() macro, which manually checks each TYPALIGN_* char to translate that into the alignment bytes for the given type. Effectively, this commit changes those to TYPEALIGN calls, which are branchless and only perform some simple arithmetic with some bit-twiddling. The removed branches were often mispredicted by CPUs, especially so in real-world tables which often contain a mishmash of different types with different alignment requirements. Author: David Rowley Reviewed-by: Andres Freund, Victor Yegorov Discussion: https://postgr.es/m/CAApHDvrBztXP3yx=NKNmo3xwFAFhEdyPnvrDg3=M0RhDs+4vYw@mail.gmail.com |
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| expected | ||
| sql | ||
| t | ||
| .gitignore | ||
| amcheck--1.1--1.2.sql | ||
| amcheck--1.2--1.3.sql | ||
| amcheck--1.3--1.4.sql | ||
| amcheck--1.0--1.1.sql | ||
| amcheck--1.0.sql | ||
| amcheck.control | ||
| Makefile | ||
| meson.build | ||
| verify_heapam.c | ||
| verify_nbtree.c | ||