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https://issues.apache.org/jira/browse/PHOENIX-4841?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=16575666#comment-16575666
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Thomas D'Silva commented on PHOENIX-4841:
-----------------------------------------
[~jamestaylor]
For this example, the query doesn't optimize the columns into the start/stop
key of the scan. The issue is how {{ComparisonExpression}} compares
{{RowValueConstructorExpression}} that have columns with different sort orders.
Here is the explain plan:
{code}
CLIENT PARALLEL 1-WAY FULL SCAN OVER N000001
SERVER FILTER BY FIRST KEY ONLY AND (B, C) > (TO_VARCHAR('b'), '3')
{code}
In {{ComparisonExpression}} when we compare two RVCs should we compare the
parts of the lhs and rhs byte arrays that have the same sort order only? If
the sort order is DESC we should also invert the comparator.
I think we would have to do something similar to what
{{WhereOptimizer.pushKeyExpressionsToScan}} is doing
{code}
// If the sort order changes, we must clip the portion with the same sort order
// and invert the key ranges and swap the upper and lower
bounds.
List<KeyRange> leftRanges = clipLeft(schema,
slot.getPKPosition() + slotOffset - clipLeftSpan, clipLeftSpan, keyRanges, ptr);
keyRanges = clipRight(schema, slot.getPKPosition() +
slotOffset - 1, keyRanges, leftRanges, ptr);
if (prevSortOrder == SortOrder.DESC) {
leftRanges = invertKeyRanges(leftRanges);
}
{code}
> Filters that uses RVC with pk columns where with DESC sort order don't work
> correctly
> -------------------------------------------------------------------------------------
>
> Key: PHOENIX-4841
> URL: https://issues.apache.org/jira/browse/PHOENIX-4841
> Project: Phoenix
> Issue Type: Bug
> Affects Versions: 4.15.0, 5.1.0
> Reporter: Thomas D'Silva
> Priority: Major
>
> If we filter on pk columns where one of the columns is DESC, we don't get the
> expected results. If the PK columns are of sorted by ASC we get the correct
> results. For eg. the following test fails:
> {code}
> @Test
> public void testRVCWithDescAndAscPK() throws Exception {
> String fullTableName = generateUniqueName();
> // create base table and global view using global connection
> try (Connection conn = DriverManager.getConnection(getUrl())) {
> Statement stmt = conn.createStatement();
> stmt.execute("CREATE TABLE " + fullTableName + "(\n" +
> " A VARCHAR NOT NULL,\n" +
> " B VARCHAR NOT NULL,\n" +
> " C VARCHAR NOT NULL,\n" +
> " CONSTRAINT PK PRIMARY KEY (A, B DESC, C))");
>
> conn.createStatement().execute("UPSERT INTO " + fullTableName + "
> VALUES ('x', 'd', '1')");
> conn.createStatement().execute("UPSERT INTO " + fullTableName + "
> VALUES ('x', 'c', '2')");
> conn.createStatement().execute("UPSERT INTO " + fullTableName + "
> VALUES ('x', 'b', '3')");
> conn.createStatement().execute("UPSERT INTO " + fullTableName + "
> VALUES ('x', 'b', '4')");
> conn.createStatement().execute("UPSERT INTO " + fullTableName + "
> VALUES ('x', 'a', '4')");
> conn.commit();
> }
> // validate that running query using global view gives same results
> try (Connection conn = DriverManager.getConnection(getUrl())) {
> ResultSet rs =
> conn.createStatement().executeQuery(
> "SELECT B, C FROM " + fullTableName + " WHERE (B, C)
> > ('b', '3')");
> assertTrue(rs.next());
> assertEquals("d", rs.getString(1));
> assertEquals("1", rs.getString(2));
> assertTrue(rs.next());
> assertEquals("c", rs.getString(1));
> assertEquals("2", rs.getString(2));
> assertTrue(rs.next());
> assertEquals("b", rs.getString(1));
> assertEquals("4", rs.getString(2));
> assertFalse(rs.next());
> }
> }
> {code}
> The comparison expression for the above query is
> {code}
> (PK[-1], PK[-1]) > (TO_VARCHAR('b'), '3')
> {code}
> When the first row is evaluated the lhs bytes is:
> {code}
> [-101, -1, 49]
> {code}
> and rhs bytes:
> {code}
> [-99, -1, 51]
> {code}
> We invert the bytes of the B column but since the greater than comparison
> operator usedthe row is filtered out (even though it should be returned).
> [~jamestaylor]
> When a column is DESC order do we need to rewrite the comparison expression?
> Instead of
> {code}
> WHERE (B, C) > ('b', '3')
> {code}
> we need something like
> {code}
> WHERE B<~'b' OR (B=~'b' AND C>'3')
> {code}
> Is there a better way to handle this?
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