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https://issues.apache.org/jira/browse/PHOENIX-5065?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=16713453#comment-16713453
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William Shen commented on PHOENIX-5065:
---------------------------------------
With the explain plan, it seems like when there are multiple values involved,
the IN operator translates IS NULL instead of = NULL for the empty string?
{noformat}
0: jdbc:phoenix:labs-darth-journalnode-lv-101> explain SELECT COUNT(*) FROM
SYSTEM.CATALOG WHERE TENANT_ID = '';
+--------------------------------------+-----------------+----------------+--------------+
| PLAN | EST_BYTES_READ | EST_ROWS_READ |
EST_INFO_TS |
+--------------------------------------+-----------------+----------------+--------------+
| DEGENERATE SCAN OVER SYSTEM.CATALOG | null | null |
null |
+--------------------------------------+-----------------+----------------+--------------+
1 row selected (0.022 seconds)
0: jdbc:phoenix:labs-darth-journalnode-lv-101> explain SELECT COUNT(*) FROM
SYSTEM.CATALOG WHERE TENANT_ID = null;
+--------------------------------------+-----------------+----------------+--------------+
| PLAN | EST_BYTES_READ | EST_ROWS_READ |
EST_INFO_TS |
+--------------------------------------+-----------------+----------------+--------------+
| DEGENERATE SCAN OVER SYSTEM.CATALOG | null | null |
null |
+--------------------------------------+-----------------+----------------+--------------+
1 row selected (0.027 seconds)
0: jdbc:phoenix:labs-darth-journalnode-lv-101> explain SELECT COUNT(*) FROM
SYSTEM.CATALOG WHERE TENANT_ID is null;
+----------------------------------------------------------------------+-----------------+----------------+--------------+
| PLAN |
EST_BYTES_READ | EST_ROWS_READ | EST_INFO_TS |
+----------------------------------------------------------------------+-----------------+----------------+--------------+
| CLIENT 1-CHUNK PARALLEL 1-WAY RANGE SCAN OVER SYSTEM.CATALOG [null] | null
| null | null |
| SERVER FILTER BY FIRST KEY ONLY | null
| null | null |
| SERVER AGGREGATE INTO SINGLE ROW | null
| null | null |
+----------------------------------------------------------------------+-----------------+----------------+--------------+
3 rows selected (0.02 seconds)
0: jdbc:phoenix:labs-darth-journalnode-lv-101> explain SELECT COUNT(*) FROM
SYSTEM.CATALOG WHERE TENANT_ID in (null);
+--------------------------------------+-----------------+----------------+--------------+
| PLAN | EST_BYTES_READ | EST_ROWS_READ |
EST_INFO_TS |
+--------------------------------------+-----------------+----------------+--------------+
| DEGENERATE SCAN OVER SYSTEM.CATALOG | null | null |
null |
+--------------------------------------+-----------------+----------------+--------------+
1 row selected (0.04 seconds)
0: jdbc:phoenix:labs-darth-journalnode-lv-101> explain SELECT COUNT(*) FROM
SYSTEM.CATALOG WHERE TENANT_ID in ('');
+--------------------------------------+-----------------+----------------+--------------+
| PLAN | EST_BYTES_READ | EST_ROWS_READ |
EST_INFO_TS |
+--------------------------------------+-----------------+----------------+--------------+
| DEGENERATE SCAN OVER SYSTEM.CATALOG | null | null |
null |
+--------------------------------------+-----------------+----------------+--------------+
1 row selected (0.02 seconds)
0: jdbc:phoenix:labs-darth-journalnode-lv-101> explain SELECT COUNT(*) FROM
SYSTEM.CATALOG WHERE TENANT_ID in ('', 'FOO');
+-----------------------------------------------------------------------------------------+-----------------+----------------+--------------+
| PLAN
| EST_BYTES_READ | EST_ROWS_READ | EST_INFO_TS |
+-----------------------------------------------------------------------------------------+-----------------+----------------+--------------+
| CLIENT 1-CHUNK PARALLEL 1-WAY SKIP SCAN ON 2 KEYS OVER SYSTEM.CATALOG [null]
- ['FOO'] | null | null | null |
| SERVER FILTER BY FIRST KEY ONLY
| null | null | null |
| SERVER AGGREGATE INTO SINGLE ROW
| null | null | null |
+-----------------------------------------------------------------------------------------+-----------------+----------------+--------------+
{noformat}
> Inconsistent treatment of NULL and empty string
> -----------------------------------------------
>
> Key: PHOENIX-5065
> URL: https://issues.apache.org/jira/browse/PHOENIX-5065
> Project: Phoenix
> Issue Type: Bug
> Affects Versions: 4.14.1
> Reporter: Geoffrey Jacoby
> Priority: Major
>
> Phoenix doesn't handle NULLs consistently with other SQL dialects, and it
> doesn't handle them consistently internally either.
> In PHOENIX-2422, [~jamestaylor] mentioned that Phoenix's intended behavior is
> for empty string and NULL to be equivalent. That's inconsistent with other
> SQL dialects (in which NULL is never equal to anything, including itself),
> but if that's our documented behavior, then that's fine unless PHOENIX-2422
> to change it is ever worked.
> But consider the following queries:
> {code:java}
> SELECT COUNT(*) FROM SYSTEM.CATALOG WHERE TENANT_ID = '';
> -- Returns 0 rows
> SELECT COUNT(*) FROM SYSTEM.CATALOG WHERE TENANT_ID IS NULL;
> -- Returns some number of rows. Call it N
> SELECT COUNT(*) FROM SYSTEM.CATALOG WHERE TENANT_ID IN ('');
> -- Returns 0 rows
> SELECT COUNT(*) FROM SYSTEM.CATALOG WHERE TENANT_ID IN ('', 'FOO');
> -- Returns N rows. Note that FOO does not exist, and is just a nonsense string
> SELECT COUNT(*) FROM SYSTEM.CATALOG WHERE TENANT_ID = '' OR TENANT_ID = 'FOO'
> --Returns 0 rows, but slowly
> {code}
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