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spanner-jdbc: Support query hints #6553

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Merged
olavloite merged 1 commit into from
Oct 25, 2019
Merged

spanner-jdbc: Support query hints #6553

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22 changes: 22 additions & 0 deletions ...oogle-cloud-spanner-jdbc/src/main/java/com/google/cloud/spanner/jdbc/StatementParser.java
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Original file line number Diff line number Diff line change
Expand Up @@ -239,6 +239,10 @@ boolean isDdlStatement(String sql) {
* @return <code>true</code> if the statement is a SELECT statement (i.e. starts with 'SELECT').
*/
boolean isQuery(String sql) {
// Skip any query hints at the beginning of the query.
if (sql.startsWith("@")) {
sql = removeStatementHint(sql);
}
return statementStartsWith(sql, selectStatements);
}

Expand Down Expand Up @@ -378,4 +382,22 @@ static String removeCommentsAndTrim(String sql) {
}
return res.toString().trim();
}

/** Removes any statement hints at the beginning of the statement. */
static String removeStatementHint(String sql) {
// Valid statement hints at the beginning of a SQL statement can only contain a fixed set of
// possible values. Although it is possible to add a @{FORCE_INDEX=...} as a statement hint, the
// only allowed value is _BASE_TABLE. This means that we can safely assume that the statement
// hint will not contain any special characters, for example a closing curly brace, and
// that we can keep the check simple by just searching for the first occurrence of a closing
// curly brace at the end of the statement hint.
int startStatementHintIndex = sql.indexOf('{');
int endStatementHintIndex = sql.indexOf('}');
if (startStatementHintIndex == -1 || startStatementHintIndex > endStatementHintIndex) {
// Looks like an invalid statement hint. Just ignore at this point and let the caller handle
// the invalid query.
return sql;
}
return removeCommentsAndTrim(sql.substring(endStatementHintIndex + 1));
}
}
22 changes: 22 additions & 0 deletions ...e-cloud-spanner-jdbc/src/test/java/com/google/cloud/spanner/jdbc/StatementParserTest.java
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Original file line number Diff line number Diff line change
Expand Up @@ -292,6 +292,28 @@ public void testIsQuery() {
.isQuery());
}

@Test
public void testQueryHints() {
// Valid query hints.
assertTrue(parser.isQuery("@{JOIN_METHOD=HASH_JOIN} SELECT * FROM PersonsTable"));
assertTrue(parser.isQuery("@ {JOIN_METHOD=HASH_JOIN} SELECT * FROM PersonsTable"));
assertTrue(parser.isQuery("@{ JOIN_METHOD=HASH_JOIN} SELECT * FROM PersonsTable"));
assertTrue(parser.isQuery("@{JOIN_METHOD=HASH_JOIN } SELECT * FROM PersonsTable"));
assertTrue(parser.isQuery("@{JOIN_METHOD=HASH_JOIN}\nSELECT * FROM PersonsTable"));
assertTrue(parser.isQuery("@{\nJOIN_METHOD = HASH_JOIN \t}\n\t SELECT * FROM PersonsTable"));
assertTrue(
parser.isQuery(
"@{JOIN_METHOD=HASH_JOIN}\n -- Single line comment\nSELECT * FROM PersonsTable"));
assertTrue(
parser.isQuery(
"@{JOIN_METHOD=HASH_JOIN}\n /* Multi line comment\n with more comments\n */SELECT * FROM PersonsTable"));

// Invalid query hints.
assertFalse(parser.isQuery("@{JOIN_METHOD=HASH_JOIN SELECT * FROM PersonsTable"));
assertFalse(parser.isQuery("@JOIN_METHOD=HASH_JOIN} SELECT * FROM PersonsTable"));
assertFalse(parser.isQuery("@JOIN_METHOD=HASH_JOIN SELECT * FROM PersonsTable"));
}

@Test
public void testIsUpdate_InsertStatements() {
assertFalse(parser.isUpdateStatement(""));
Expand Down