From 9354f5b76acf37c96ed0173ff8ab3e415bae2b04 Mon Sep 17 00:00:00 2001 From: Tom Lane Date: Thu, 25 Aug 2011 14:33:08 -0400 Subject: [PATCH] Fix psql lexer to avoid use of backtracking. Per previous experimentation, backtracking slows down lexing performance significantly (by about a third). It's usually pretty easy to avoid, just need to have rules that accept an incomplete construct and do whatever the lexer would have done otherwise. The backtracking was introduced by the patch that added quoted variable substitution. Back-patch to 9.0 where that was added. --- src/bin/psql/psqlscan.l | 33 ++++++++++++++++++++++++++++++++- 1 file changed, 32 insertions(+), 1 deletion(-) diff --git a/src/bin/psql/psqlscan.l b/src/bin/psql/psqlscan.l index dfde8db19b..5fefa475af 100644 --- a/src/bin/psql/psqlscan.l +++ b/src/bin/psql/psqlscan.l @@ -722,6 +722,23 @@ other . escape_variable(true); } + /* + * These rules just avoid the need for scanner backup if one of the + * two rules above fails to match completely. + */ + +:'[A-Za-z0-9_]* { + /* Throw back everything but the colon */ + yyless(1); + ECHO; + } + +:\"[A-Za-z0-9_]* { + /* Throw back everything but the colon */ + yyless(1); + ECHO; + } + /* * Back to backend-compatible rules. */ @@ -912,7 +929,7 @@ other . } } -:[A-Za-z0-9_]* { +:[A-Za-z0-9_]+ { /* Possible psql variable substitution */ if (option_type == OT_VERBATIM) ECHO; @@ -959,6 +976,20 @@ other . } } +:'[A-Za-z0-9_]* { + /* Throw back everything but the colon */ + yyless(1); + ECHO; + BEGIN(xslashdefaultarg); + } + +:\"[A-Za-z0-9_]* { + /* Throw back everything but the colon */ + yyless(1); + ECHO; + BEGIN(xslashdefaultarg); + } + "|" { ECHO; if (option_type == OT_FILEPIPE) -- 2.40.0