asolimando commented on code in PR #4460:
URL: https://github.com/apache/calcite/pull/4460#discussion_r2311826564
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core/src/main/java/org/apache/calcite/rex/RexSimplify.java:
##########
@@ -500,17 +501,67 @@ private RexNode simplifyDivide(RexCall e) {
private RexNode simplifyLike(RexCall e, RexUnknownAs unknownAs) {
if (e.operands.get(1) instanceof RexLiteral) {
final RexLiteral literal = (RexLiteral) e.operands.get(1);
- if ("%".equals(literal.getValueAs(String.class))) {
- // "x LIKE '%'" simplifies to "x = x"
+ String likeStr = requireNonNull(literal.getValueAs(String.class));
+ Pattern pattern = Pattern.compile("%+");
+ String value = pattern.matcher(likeStr).replaceAll("%");
+ if ("%".equals(value)) {
+ // "x LIKE '%'" or "x LIKE '%...'" simplifies to "x = x"
final RexNode x = e.operands.get(0);
return simplify(
rexBuilder.makeCall(
e.getParserPosition(), SqlStdOperatorTable.EQUALS, x, x),
unknownAs);
}
+ // simplify "x LIKE '%%\%%a%%%'" to "x LIKE '%\%%a%'", default escape is
'\'
+ if (e.operands.size() == 2) {
+ e = (RexCall) rexBuilder
+ .makeCall(e.getParserPosition(), e.getOperator(),
e.operands.get(0),
+ rexBuilder.makeLiteral(simplifyLikeString(likeStr, '\\',
'%')));
+ }
+ if (e.operands.size() == 3 && e.operands.get(2) instanceof RexLiteral) {
+ final RexLiteral escapeLiteral = (RexLiteral) e.operands.get(2);
+ Character escape =
requireNonNull(escapeLiteral.getValueAs(Character.class));
+ e = (RexCall) rexBuilder
+ .makeCall(e.getParserPosition(), e.getOperator(),
e.operands.get(0),
+ rexBuilder.makeLiteral(simplifyLikeString(likeStr, escape,
'%')),
+ escapeLiteral);
+ }
}
return simplifyGenericNode(e);
}
+ /**
+ * Simplifies like string with escape.
+ * A like '%%#%%A%%' escape '#' should simplify to A like '%#%%A%' escape
'#'.
+ */
+ private String simplifyLikeString(String content, char escape, char
wildcard) {
Review Comment:
Agreed, but please make sure to file a ticket with the details and examples
Mihai provided before merging, so we make sure that the effort and insight from
the reviewer isn't lost (PR comments aren't really looked at after merging).
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