Oracle 19C SHARDING- Generating Unique Sequence Numbers Across Shards for SHARD KEY Column (Doc ID 2468934.1)

Last updated on JULY 20, 2024

Applies to:

Goal

For the purposes of this document, the following fictitious environment is used as an example to describe the procedure:

Shard Names: SH23,SH24
Shard Groups: TEST1
Network Name: sales.sdbs1.oradbcloud
Region Name: regionora
Catalog Database: SCAT
Schema Name: TEST
Table Name: CUSTOMERS

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Generating Shard key values using Unique Sequence Numbers Across Shards.

Before Oracle Database 19c, if you needed a unique number across shards you had to manage it yourself. In Oracle Database 19c, Oracle Sharding allows you to independently generate sequence numbers on each shard which are unique across all shards.

To support this feature, new SEQUENCE object clauses, SHARD and NOSHARD, are included in the SEQUENCE object DDL syntax, as shown in the following CREATE statement syntax.

CREATE | ALTER SEQUENCE [ schema. ]sequence
   [ { INCREMENT BY | START WITH } integer
   | { MAXVALUE integer | NOMAXVALUE }
   | { MINVALUE integer | NOMINVALUE }
   | { CYCLE | NOCYCLE }
   | { CACHE integer | NOCACHE }
   | { ORDER | NOORDER }
   | { SCALE {EXTEND | NOEXTEND} | NOSCALE}
   | { SHARD {EXTEND | NOEXTEND} | NOSHARD} 
   ]

Solution

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