[
https://issues.apache.org/jira/browse/CASSANDRA-8877?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=17569390#comment-17569390
]
Andres de la Peña commented on CASSANDRA-8877:
----------------------------------------------
The proposed patch provides CQL support for getting the writetime/ttl of the
cells of:
* Entire collections/UDTs
* Single collections/UDTs elements
* Slices of collection elements
||PR||CI||
|[trunk|https://github.com/apache/cassandra/pull/1739]|[j8|https://app.circleci.com/pipelines/github/adelapena/cassandra/1943/workflows/947857e9-c2a5-4ad3-9c4c-c99869dd868b]
[j11|https://app.circleci.com/pipelines/github/adelapena/cassandra/1943/workflows/2851c046-e704-4c51-a8a4-b995475530be]|
It is based on an old patch that I wrote some time ago with the invaluable help
of [~blerer].
Here is an example of the behaviour for frozen collections:
{code}
CREATE TABLE IF NOT EXISTS t (k int PRIMARY KEY, s frozen<set<int>>);
INSERT INTO t (k, s) VALUES (1, {1, 2, 3}) USING TIMESTAMP 100 AND TTL 10000;
SELECT s, WRITETIME(s), TTL(s) FROM t;
s | writetime(s) | ttl(s)
-----------+--------------+--------
{1, 2, 3} | 100 | 10000
SELECT s[2], WRITETIME(s[2]), TTL(s[2]) FROM t;
s[2] | writetime(s[2]) | ttl(s[2])
------+-----------------+-----------
2 | 100 | 10000
SELECT s[4], WRITETIME(s[4]), TTL(s[4]) FROM t;
s[4] | writetime(s[4]) | ttl(s[4])
------+-----------------+-----------
null | null | null
SELECT s[2..], WRITETIME(s[2..]), TTL(s[2..]) FROM t;
s[2..] | writetime(s[2..]) | ttl(s[2..])
--------+-------------------+-------------
{2, 3} | 100 | 9897
{code}
For not-frozen collections:
{code}
CREATE TABLE IF NOT EXISTS t (k int PRIMARY KEY, s set<int>);
INSERT INTO t (k, s) VALUES (1, {1, 2}) USING TIMESTAMP 100 AND TTL 10000;
UPDATE t USING TIMESTAMP 200 AND TTL 20000 SET s += {3} WHERE k=1;
SELECT s, WRITETIME(s), TTL(s) FROM t;
s | writetime(s) | ttl(s)
-----------+-----------------+-----------------------
{1, 2, 3} | [100, 100, 200] | [10000, 10000, 20000]
SELECT s[2], WRITETIME(s[2]), TTL(s[2]) FROM t;
s[2] | writetime(s[2]) | ttl(s[2])
------+-----------------+-----------
2 | 100 | 10000
SELECT s[4], WRITETIME(s[4]), TTL(s[4]) FROM t;
s[4] | writetime(s[4]) | ttl(s[4])
------+-----------------+-----------
null | null | null
SELECT s[2..], WRITETIME(s[2..]), TTL(s[2..]) FROM t;
s[2..] | writetime(s[2..]) | ttl(s[2..])
--------+-------------------+----------------
{2, 3} | [100, 200] | [10000, 20000]
{code}
For frozen UDTs:
{code}
CREATE TYPE udt (f1 int, f2 int, f3 int);
CREATE TABLE t (k int PRIMARY KEY, t frozen<udt>);
INSERT INTO t (k, t) VALUES (1, {f1: 1, f2: 2}) USING TIMESTAMP 100 AND TTL
10000;
SELECT t, WRITETIME(t), TTL(t) FROM t;
t | writetime(t) | ttl(t)
--------------------------+--------------+--------
{f1: 1, f2: 2, f3: null} | 100 | 10000
SELECT t.f1, WRITETIME(t.f1), TTL(t.f1) FROM t;
t.f1 | writetime(t.f1) | ttl(t.f1)
------+-----------------+-----------
1 | 100 | 10000
SELECT t.f2, WRITETIME(t.f2), TTL(t.f2) FROM t;
t.f2 | writetime(t.f2) | ttl(t.f2)
------+-----------------+-----------
2 | 100 | 10000
SELECT t.f3, WRITETIME(t.f3), TTL(t.f3) FROM t;
t.f3 | writetime(t.f3) | ttl(t.f3)
------+-----------------+-----------
null | null | null
{code}
For not-frozen UDTs:
{code}
CREATE TYPE udt (f1 int, f2 int, f3 int);
CREATE TABLE t (k int PRIMARY KEY, t udt);
INSERT INTO t (k, t) VALUES (1, {f1: 1}) USING TIMESTAMP 100 AND TTL 10000;
UPDATE t USING TIMESTAMP 200 AND TTL 20000 SET t.f2 = 2 WHERE k = 1;
SELECT t, WRITETIME(t), TTL(t) FROM t;
t | writetime(t) | ttl(t)
--------------------------+------------------+----------------------
{f1: 1, f2: 2, f3: null} | [100, 200, None] | [10000, 20000, None]
SELECT t.f1, WRITETIME(t.f1), TTL(t.f1) FROM t;
t.f1 | writetime(t.f1) | ttl(t.f1)
------+-----------------+-----------
1 | 100 | 10000
SELECT t.f2, WRITETIME(t.f2), TTL(t.f2) FROM t;
t.f2 | writetime(t.f2) | ttl(t.f2)
------+-----------------+-----------
2 | 200 | 20000
SELECT t.f3, WRITETIME(t.f3), TTL(t.f3) FROM t;
t.f3 | writetime(t.f3) | ttl(t.f3)
------+-----------------+-----------
null | null | null
{code}
As for the {{MAXWRITETIME}} function added by CASSANDRA-17425, I have adapted
it so it can also used on items of a collection. It's possible to query things
like {{MAXWRITETTIME(phones[2..4])}} or {{MAXWRITETTIME(user.name)}}. However,
I think we should try to get rid of that function and instead provide generic
functions to aggregate the elements of a collection, so instead of
{{MAXWRITETTIME(phones[2..4])}} we would write something like
{{GREATEST(WRITETTIME(phones[2..4]))}}. In any case, I think that should
probably done in a followup ticket. [~yifanc] wdyt?
> Ability to read the TTL and WRITE TIME of an element in a collection
> --------------------------------------------------------------------
>
> Key: CASSANDRA-8877
> URL: https://issues.apache.org/jira/browse/CASSANDRA-8877
> Project: Cassandra
> Issue Type: Improvement
> Components: Legacy/CQL
> Reporter: Drew Kutcharian
> Assignee: Andres de la Peña
> Priority: Low
> Fix For: 4.x
>
>
> Currently it's possible to set the TTL and WRITE TIME of an element in a
> collection using CQL, but there is no way to read them back.
--
This message was sent by Atlassian Jira
(v8.20.10#820010)
---------------------------------------------------------------------
To unsubscribe, e-mail: [email protected]
For additional commands, e-mail: [email protected]
