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In the standard numeric division algorithm, the inner loop multiplies the divisor by the next quotient digit and subtracts that from the working dividend. As suggested by the original code comment, the separate "carry" and "borrow" variables (from the multiplication and subtraction steps respectively) can be folded together into a single variable. Doing so significantly improves performance, as well as simplifying the code. Dean Rasheed, reviewed by Tom Lane. Discussion: https://postgr.es/m/CAEZATCVwsBi-ND-t82Cuuh1=8ee6jdOpzsmGN+CUZB6yjLg9jw@mail.gmail.com |
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| .. | ||
| activity | ||
| adt | ||
| cache | ||
| error | ||
| fmgr | ||
| hash | ||
| init | ||
| mb | ||
| misc | ||
| mmgr | ||
| resowner | ||
| sort | ||
| time | ||
| .gitignore | ||
| errcodes.txt | ||
| Gen_dummy_probes.pl | ||
| Gen_dummy_probes.pl.prolog | ||
| Gen_dummy_probes.sed | ||
| Gen_fmgrtab.pl | ||
| generate-errcodes.pl | ||
| Makefile | ||
| probes.d | ||
| README.Gen_dummy_probes | ||
# Generating dummy probes If Postgres isn't configured with dtrace enabled, we need to generate dummy probes for the entries in probes.d, that do nothing. This is accomplished in Unix via the sed script `Gen_dummy_probes.sed`. We used to use this in MSVC builds using the perl utility `psed`, which mimicked sed. However, that utility disappeared from Windows perl distributions and so we converted the sed script to a perl script to be used in MSVC builds. We still keep the sed script as the authoritative source for generating these dummy probes because except on Windows perl is not a hard requirement when building from a tarball. So, if you need to change the way dummy probes are generated, first change the sed script, and when it's working generate the perl script. This can be accomplished by using the perl utility s2p. s2p is no longer part of the perl core, so it might not be on your system, but it is available on CPAN and also in many package systems. e.g. on Fedora it can be installed using `cpan App::s2p` or `dnf install perl-App-s2p`. The Makefile contains a recipe for regenerating Gen_dummy_probes.pl, so all you need to do is once you have s2p installed is `make Gen_dummy_probes.pl` Note that in a VPATH build this will generate the file in the vpath tree, not the source tree.