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HHH-11614 : Update migration guide with example for converting variable-length strings to PostgreSQL Large Objects

This commit is contained in:
Gail Badner 2017-09-08 21:36:05 -07:00
parent cf89391e06
commit a9b0305004
1 changed files with 40 additions and 5 deletions
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39
migration-guide.adoc
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@ -125,7 +125,7 @@ PostgreSQL dialect with:
[source,java]
----
public SqlTypeDescriptor getSqlTypeDescriptorOverride(int sqlCode) {
if(sqlCode == Types.CLOB){
if( sqlCode == Types.CLOB ){
return ClobTypeDescriptor.CLOB_BINDING;
}
return super.getSqlTypeDescriptorOverride( sqlCode );
@ -133,7 +133,42 @@ public SqlTypeDescriptor getSqlTypeDescriptorOverride(int sqlCode) {
----
In addition, any `Clob` values and values for `String`, `character[]`, `Character[]` attributes that are annotated with
`@Lob` that were persisted using 5.2.9 or 5.2.10 should be updated to store the values as PostgreSQL Large Objects.
`@Lob` that were stored as variable-length character strings using 5.2.9 or 5.2.10 should be updated to store the values
as PostgreSQL Large Objects before migrating to 5.2.11.
For example, if variable-length character strings were stored by 5.2.9 or 5.2.10 for the following mapping:
[source,java]
----
@Entity(name = "TestEntity")
@Table(name = "TEST_ENTITY")
public static class TestEntity {
@Id
@GeneratedValue
private long id;
@Lob
String firstLobField;
@Lob
String secondLobField;
@Lob
Clob clobField;
...
}
----
the variable-length character strings can be converted to PostgreSQL Large Objects by executing the following SQL:
[source,sql]
----
update test_entity
set clobfield = lo_from_bytea( 0, cast( clobfield as bytea ) ),
firstlobfield = lo_from_bytea( 0, cast( firstlobfield as bytea ) ),
secondlobfield = lo_from_bytea( 0, cast( secondlobfield as bytea ) )
----
== Misc