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[FLINK-39402][table] Fix LIKE quick path ignoring default escape character '\' #27898

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[FLINK-39402][table] Fix LIKE quick path ignoring default escape character '\' #27898

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79 changes: 45 additions & 34 deletions ...ble-planner/src/main/scala/org/apache/flink/table/planner/codegen/calls/LikeCallGen.scala
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Original file line number Diff line number Diff line change
Expand Up @@ -54,47 +54,58 @@ class LikeCallGen extends CallGenerator {
terms =>
val pattern = operands(1).literalValue.get.toString
var newPattern: String = pattern
val allowQuick = if (operands.length == 2) {
!pattern.contains("_")
} else {
val escape = operands(2).literalValue.get.toString
if (escape.isEmpty) {
!pattern.contains("_")
val allowQuick = {
// Determine escape character:
// - operands.length == 2 (no ESCAPE clause): default escape is '\'
// - operands.length == 3 with empty escape: no escape character
// - operands.length == 3 with non-empty escape: use specified escape
val escapeCharOpt: Option[Char] = if (operands.length == 2) {
Some('\\')
} else {
if (escape.length > 1) {
throw SqlLikeUtils.invalidEscapeCharacter(escape)
val escape = operands(2).literalValue.get.toString
if (escape.isEmpty) {
None
} else {
if (escape.length > 1) {
throw SqlLikeUtils.invalidEscapeCharacter(escape)
}
Some(escape.charAt(escape.length - 1))
}
val escapeChar = escape.charAt(escape.length - 1)
var matched = true
var i = 0
val newBuilder = new StringBuilder
while (i < pattern.length && matched) {
val c = pattern.charAt(i)
if (c == escapeChar) {
if (i == (pattern.length - 1)) {
throw SqlLikeUtils.invalidEscapeSequence(pattern, i)
}
val nextChar = pattern.charAt(i + 1)
if (nextChar == '%') {
}

escapeCharOpt match {
case None => !pattern.contains("_")
case Some(escapeChar) =>
var matched = true
var i = 0
val newBuilder = new StringBuilder
while (i < pattern.length && matched) {
val c = pattern.charAt(i)
if (c == escapeChar) {
if (i == (pattern.length - 1)) {
throw SqlLikeUtils.invalidEscapeSequence(pattern, i)
}
val nextChar = pattern.charAt(i + 1)
if (nextChar == '%') {
matched = false
} else if ((nextChar == '_') || (nextChar == escapeChar)) {
newBuilder.append(nextChar)
i += 1
} else {
throw SqlLikeUtils.invalidEscapeSequence(pattern, i)
}
} else if (c == '_') {
matched = false
} else if ((nextChar == '_') || (nextChar == escapeChar)) {
newBuilder.append(nextChar)
i += 1
} else {
throw SqlLikeUtils.invalidEscapeSequence(pattern, i)
newBuilder.append(c)
}
} else if (c == '_') {
matched = false
} else {
newBuilder.append(c)
i += 1
}
i += 1
}

if (matched) {
newPattern = newBuilder.toString
}
matched
if (matched) {
newPattern = newBuilder.toString
}
matched
}
}

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26 changes: 25 additions & 1 deletion ...anner/src/test/scala/org/apache/flink/table/planner/expressions/ScalarFunctionsTest.scala
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Original file line number Diff line number Diff line change
Expand Up @@ -408,11 +408,28 @@ class ScalarFunctionsTest extends ScalarTypesTestBase {
testAllApis("abcxxxdef".like("%abc%qef%"), "'abcxxxdef' LIKE '%abc%qef%'", "FALSE")
testAllApis("abcxxxdef".like("abc%qef"), "'abcxxxdef' LIKE 'abc%qef'", "FALSE")

// reported in FLINK-36100
// reported in FLINK-36100: verify default escape char '\' behavior
// \_ means literal '_', \% means literal '%'
testAllApis("TE_ST".like("%E_S%"), "'TE_ST' LIKE '%E_S%'", "TRUE")
testAllApis("TE-ST".like("%E_S%"), "'TE-ST' LIKE '%E_S%'", "TRUE")
testAllApis("TE_ST".like("%E\\_S%"), "'TE_ST' LIKE '%E\\_S%'", "TRUE")
testAllApis("TE-ST".like("%E\\_S%"), "'TE-ST' LIKE '%E\\_S%'", "FALSE")
testAllApis("TE%ST".like("TE\\%ST"), "'TE%ST' LIKE 'TE\\%ST'", "TRUE")
testAllApis("TExST".like("TE\\%ST"), "'TExST' LIKE 'TE\\%ST'", "FALSE")

// escape character at the end
testExpectedAllApisException(
"TE-ST".like("%E-S%\\"),
"'TE-ST' LIKE '%E-S%\\'",
"",
classOf[RuntimeException])

// invalid character after escape character
testExpectedAllApisException(
"TEST".like("%E\\S%"),
"'TEST' LIKE '%E\\S%'",
"Invalid escape",
classOf[RuntimeException])
}

@Test
Expand All @@ -429,6 +446,13 @@ class ScalarFunctionsTest extends ScalarTypesTestBase {

@Test
def testLikeWithEscape(): Unit = {
// empty ESCAPE string: no escape character, _ and % retain wildcard semantics
testAllApis("abc".like("abc", ""), "'abc' LIKE 'abc' ESCAPE ''", "TRUE")
testAllApis("abd".like("abc", ""), "'abd' LIKE 'abc' ESCAPE ''", "FALSE")
testAllApis("abcdef".like("abc%", ""), "'abcdef' LIKE 'abc%' ESCAPE ''", "TRUE")
testAllApis("abcdef".like("%def", ""), "'abcdef' LIKE '%def' ESCAPE ''", "TRUE")
testAllApis("abcdef".like("%cd%", ""), "'abcdef' LIKE '%cd%' ESCAPE ''", "TRUE")
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@raminqaf raminqaf Apr 7, 2026

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Can we add a test for this case please

'abc_def' LIKE 'abc_def' ESCAPE ''


testAllApis('f23.like("&%Th_s%", "&"), "f23 LIKE '&%Th_s%' ESCAPE '&'", "TRUE")
testAllApis('f23.like("&%%is a%", "&"), "f23 LIKE '&%%is a%' ESCAPE '&'", "TRUE")
testAllApis('f0.like("Th_s%", "&"), "f0 LIKE 'Th_s%' ESCAPE '&'", "TRUE")
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