[DERBY-6550] Bulk-insert causes identity columns to cycle when they shouldn't

• Type: Bug
• Status: Resolved
• Priority: Major
• Resolution: Cannot Reproduce
• Affects Version/s: 10.11.1.1
• Component/s: SQL
• Urgency: Normal
• Bug behavior facts: Deviation from standard
• Assignee: Danoja Dias
• Reporter: Richard N. Hillegas
• Created: 23/Apr/14 20:34
• Updated: 01/Aug/16 06:23
• Resolved: 09/Jun/16 03:09

Description

According to the SQL Standard, an identity column is conceptually backed by a sequence generator. If you don't specify a cycle option (and for Derby's identity column, you can't), then the identity column is supposed to NOT cycle. This is described by the following sections of the 2011 edition of the SQL Standard:

o Section 11.4 (column definition), syntax rule 16

o Section 9.26 (Creation of a sequence generator), syntax rule 13

If you aren't doing a bulk-insert, then Derby honors this contract. However, due to an optimization in InsertResultSet, this contract is not honored for bigint identity columns. Bulk-insert causes Derby to cycle past the biggest positive long value and to begin generating negative longs.

The following script shows this behavior:

connect 'jdbc:derby:memory:db;create=true';

create table t
(
    a bigint generated always as identity ( start with 9223372036854775806 ),
    b int
);

create function integerList() returns table
(
    a int,
    b int,
    c int,
    d int
)
language java parameter style derby_jdbc_result_set no sql
external name 'org.apache.derbyTesting.functionTests.tests.lang.MergeStatementTest.integerList_023';

-- this fails because bulk-insert isn't used and we go past the end of the identity column's range
insert into t( b ) values ( 1 ), ( 2 ), ( 3 ), ( 4 ), ( 5 );

-- inserting into an empty table from a table function uses bulk-insert
--
-- this should fail just like the previous statement, but it succeeds
insert into t( b ) select b from table( integerList() ) il;

select * from t;

Issue Links

• is depended upon by: DERBY-6870 Google Summer of Code 2016: Derby bug fixing
• relates to: DERBY-6852 Allow identity columns to cycle (as defined in SQL:2003)
• relates to: DERBY-6542 Improve the concurrency of identity columns by using SYS.SYSSEQUENCES