[
https://issues.apache.org/jira/browse/CASSANDRA-11068?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel
]
Andy Tolbert updated CASSANDRA-11068:
-------------------------------------
Description:
Assuming the following schema:
{code}
CREATE TABLE simple.data (
k text PRIMARY KEY,
v int
) WITH gc_grace_seconds = 300;
{code}
And the following queries:
{code}
insert into simple.data (k, v) values ('blah', 1);
delete v from simple.data where k='blah';
{code}
Performing a {{select *}} from this table will return 1 row with a null value:
{code}
cqlsh> select * from simple.data;
k | v
-----------+---------
blah | null
{code}
Prior the 3.0, if I were to do a flush, the sstable representation of this
table would include an empty cell and a tombstone:
{code}
[
{"key": "blah",
"cells": [["","",1453747038457027],
["v",1453747112,1453747112383096,"d"]]}
]
{code}
As my gc_grace_seconds value is 300, if I wait 5 minutes and perform a
compaction, the new sstable would omit the tombstone, but the empty cell would
still be present:
{code}
[
{"key": "blah",
"cells": [["","",1453747038457027]]}
]
{code}
Performing the {{select *}} query would still yield the same result because of
this.
However, in 3.2.1 this does not seem to be the behavior, after deleting the 'v'
cell, performing a flush and then waiting 5 minutes and doing a compact, what
ends up happening is that the sstable completely disappears (presumably because
there is no remaining data) and the select query emits 0 rows:
{code}
cqlsh> select * from simple.data;
k | v
-----------+---------
(0 rows)
{code}
I'm unsure if this is by design or a bug, but it does represent a change
between C* versions.
I have not tried this for a table with clustering columns yet, but I assume
that the behavior will be the same.
was:
Assuming the following schema:
{code}
CREATE TABLE simple.data (
k text PRIMARY KEY,
v int
) WITH gc_grace_seconds = 300;
{code}
And the following queries:
{code}
insert into simple.data (k, v) values ('blah', 1);
delete reading from simple.data where k='blah';
{code}
Performing a {{select *}} from this table will return 1 row with a null value:
{code}
cqlsh> select * from simple.data;
k | v
-----------+---------
blah | null
{code}
Prior the 3.0, if I were to do a flush, the sstable representation of this
table would include an empty cell and a tombstone:
{code}
[
{"key": "blah",
"cells": [["","",1453747038457027],
["v",1453747112,1453747112383096,"d"]]}
]
{code}
As my gc_grace_seconds value is 300, if I wait 5 minutes and perform a
compaction, the new sstable would omit the tombstone, but the empty cell would
still be present:
{code}
[
{"key": "blah",
"cells": [["","",1453747038457027]]}
]
{code}
Performing the {{select *}} query would still yield the same result because of
this.
However, in 3.2.1 this does not seem to be the behavior, after deleting the 'v'
cell, performing a flush and then waiting 5 minutes and doing a compact, what
ends up happening is that the sstable completely disappears (presumably because
there is no remaining data) and the select query emits 0 rows:
{code}
cqlsh> select * from simple.data;
k | v
-----------+---------
(0 rows)
{code}
I'm unsure if this is by design or a bug, but it does represent a change
between C* versions.
I have not tried this for a table with clustering columns yet, but I assume
that the behavior will be the same.
> Entire row is compacted away if remaining cells are tombstones expiring after
> gc_grace_seconds
> ----------------------------------------------------------------------------------------------
>
> Key: CASSANDRA-11068
> URL: https://issues.apache.org/jira/browse/CASSANDRA-11068
> Project: Cassandra
> Issue Type: Bug
> Reporter: Andy Tolbert
>
> Assuming the following schema:
> {code}
> CREATE TABLE simple.data (
> k text PRIMARY KEY,
> v int
> ) WITH gc_grace_seconds = 300;
> {code}
> And the following queries:
> {code}
> insert into simple.data (k, v) values ('blah', 1);
> delete v from simple.data where k='blah';
> {code}
> Performing a {{select *}} from this table will return 1 row with a null value:
> {code}
> cqlsh> select * from simple.data;
> k | v
> -----------+---------
> blah | null
> {code}
> Prior the 3.0, if I were to do a flush, the sstable representation of this
> table would include an empty cell and a tombstone:
> {code}
> [
> {"key": "blah",
> "cells": [["","",1453747038457027],
> ["v",1453747112,1453747112383096,"d"]]}
> ]
> {code}
> As my gc_grace_seconds value is 300, if I wait 5 minutes and perform a
> compaction, the new sstable would omit the tombstone, but the empty cell
> would still be present:
> {code}
> [
> {"key": "blah",
> "cells": [["","",1453747038457027]]}
> ]
> {code}
> Performing the {{select *}} query would still yield the same result because
> of this.
> However, in 3.2.1 this does not seem to be the behavior, after deleting the
> 'v' cell, performing a flush and then waiting 5 minutes and doing a compact,
> what ends up happening is that the sstable completely disappears (presumably
> because there is no remaining data) and the select query emits 0 rows:
> {code}
> cqlsh> select * from simple.data;
> k | v
> -----------+---------
> (0 rows)
> {code}
> I'm unsure if this is by design or a bug, but it does represent a change
> between C* versions.
> I have not tried this for a table with clustering columns yet, but I assume
> that the behavior will be the same.
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