Doc: improve documentation around jsonpath regular expressions

Enterprise / PostgreSQL - Tom Lane [sss.pgh.pa.us] - 19 September 2019 15:22 EDT

Provide some documentation about the differences between XQuery regular expressions and those supported by Spencer's regex engine. Since SQL now exposes XQuery regexps with the LIKE_REGEX operator, I made this a standalone section designed to help somebody who has to translate a LIKE_REGEX query to Postgres. (Eventually we might extend Spencer's engine to allow precise implementation of XQuery, but not today.)

Reference that in the jsonpath docs, provide definitions of the XQuery flag letters, and add a description of the JavaScript-inspired string literal syntax used within jsonpath. Also point out explicitly that backslashes used within like_regex patterns will need to be doubled.

This also syncs the docs with the decision implemented in commit d5b90cd64 to desupport XQuery's 'x' flag for now.

Jonathan Katz and Tom Lane

Discussion: https://postgr.es/m/CAPpHfdvDci4iqNF9fhRkTqhe-5_8HmzeLt56drH%2B_Rv2rNRqfg@mail.gmail.com

0a97edb12e Doc: improve documentation around jsonpath regular expressions.
doc/src/sgml/func.sgml | 213 ++++++++++++++++++++++++++++++++++++++++++++++++-
doc/src/sgml/json.sgml | 33 ++++++--
2 files changed, 235 insertions(+), 11 deletions(-)

Upstream: git.postgresql.org


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