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fix(bigquery-jdbc): Add escape character support for pattern matching #13259

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fix(bigquery-jdbc): Add escape character support for pattern matching #13259

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fix(bigquery-jdbc): Add escape character support for pattern matching
logachev May 22, 2026
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logachev May 22, 2026
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logachev May 24, 2026
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68 changes: 44 additions & 24 deletions ...-bigquery-jdbc/src/main/java/com/google/cloud/bigquery/jdbc/BigQueryDatabaseMetaData.java
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Original file line number Diff line number Diff line change
Expand Up @@ -5080,40 +5080,60 @@ Pattern compileSqlLikePattern(String sqlLikePattern) {
}
StringBuilder regex = new StringBuilder(sqlLikePattern.length() * 2);
regex.append('^');
boolean escaped = false;
for (int i = 0; i < sqlLikePattern.length(); i++) {
char c = sqlLikePattern.charAt(i);
switch (c) {
case '%':
regex.append(".*");
break;
case '_':
regex.append('.');
break;
case '\\':
case '.':
case '[':
case ']':
case '(':
case ')':
case '{':
case '}':
case '*':
case '+':
case '?':
case '^':
case '$':
case '|':
if (escaped) {
if (isRegexMetacharacter(c)) {
regex.append('\\').append(c);
break;
default:
} else {
regex.append(c);
break;
}
escaped = false;
} else if (c == '\\') {
escaped = true;
} else {
switch (c) {
case '%':
regex.append(".*");
break;
case '_':
regex.append('.');
break;
default:
if (isRegexMetacharacter(c)) {
regex.append('\\').append(c);
} else {
regex.append(c);
}
break;
}
}
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}
if (escaped) {
regex.append('\\').append('\\');
}
regex.append('$');
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@gemini-code-assist gemini-code-assist Bot May 22, 2026

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medium

The current implementation ignores a trailing backslash if it is the last character in the sqlLikePattern. Previously, a trailing backslash was treated as a literal character and escaped in the resulting regex. To maintain backward compatibility and handle this edge case, the code should check if the escaped flag is still true after the loop and append the escaped backslash to the regex.

    if (escaped) {
      regex.append('\\').append('\\');
    }
    regex.append('$');

return Pattern.compile(regex.toString(), Pattern.CASE_INSENSITIVE);
}

private boolean isRegexMetacharacter(char c) {
return c == '\\'
|| c == '.'
|| c == '['
|| c == ']'
|| c == '('
|| c == ')'
|| c == '{'
|| c == '}'
|| c == '*'
|| c == '+'
|| c == '?'
|| c == '^'
|| c == '$'
|| c == '|';
}
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boolean needsListing(String pattern) {
return pattern == null || pattern.contains("%") || pattern.contains("_");
}
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11 changes: 11 additions & 0 deletions ...query-jdbc/src/test/java/com/google/cloud/bigquery/jdbc/BigQueryDatabaseMetaDataTest.java
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Original file line number Diff line number Diff line change
Expand Up @@ -243,6 +243,17 @@ public void testCompileSqlLikePattern() {
assertNotNull(bracketPattern);
assertTrue(bracketPattern.matcher("array[0]").matches());
assertFalse(bracketPattern.matcher("array_0_").matches());

// Escaped wildcards
Pattern escapedUnderscore = dbMetadata.compileSqlLikePattern("test\\_table");
assertNotNull(escapedUnderscore);
assertTrue(escapedUnderscore.matcher("test_table").matches());
assertFalse(escapedUnderscore.matcher("test1table").matches());

Pattern escapedPercent = dbMetadata.compileSqlLikePattern("100\\%discount");
assertNotNull(escapedPercent);
assertTrue(escapedPercent.matcher("100%discount").matches());
assertFalse(escapedPercent.matcher("100PERCENTdiscount").matches());
Comment on lines +255 to +256
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@gemini-code-assist gemini-code-assist Bot May 22, 2026

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medium

Consider adding test cases for an escaped escape character (e.g., \\) and a trailing escape character to ensure they are handled correctly and to prevent future regressions. Before adding these, please verify the existing test suite to ensure these scenarios are not already covered.

    assertTrue(escapedPercent.matcher("100%discount").matches());
    assertFalse(escapedPercent.matcher("100PERCENTdiscount").matches());

    // Escaped escape character
    Pattern escapedBackslash = dbMetadata.compileSqlLikePattern("test\\\\table");
    assertTrue(escapedBackslash.matcher("test\\table").matches());

    // Trailing escape character
    Pattern trailingBackslash = dbMetadata.compileSqlLikePattern("test\\");
    assertTrue(trailingBackslash.matcher("test\\").matches());
References
  1. Before adding new test cases for input validation, verify the existing test suite to ensure these scenarios are not already covered.

}

@Test
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