Transition H2 data to PostgreSQL

问题

I am doing a transition from H2 database to PostgreSQL. As I found out - the SQL dump which is created when doing SCRIPT TO command on H2 contains several inappropriate constructions:

Unicode data is wrapped with function STRINGDECODE('unicode-data')
Binary & Blob data is escaped as X'binary-data' - probably hex format (Used for storing images and files directly in a database table

I managed to change my exported SQL so it is compatible with Postgres as follows:

Unicode data is wrapped with E'unicode-data'
Binary & Blob data is escaped as E'\\xbinary-data' - should be imported in 'bytea' column in Postgres

Import of data passes as it should.

I configured Hibernate to use PostgreSQL dialect, where default binary & blob type of Postgres is changed to 'bytea':

public class PostgreDialectFix extends PostgreSQLDialect {

    /**
     * Creates a new instance.
     */
    public PostgreDialectFix() {
        super();

        registerColumnType(Types.BLOB, "bytea");                    
        registerColumnType(Types.LONGVARBINARY, "bytea");           
    }
}

I also added the following to my persistense.xml:

<!-- PostgreSQL binary data usage ('false' for oid, 'true' for bytea) -->
<property name="hibernate.jdbc.use_streams_for_binary" value="true"/>

So everything compiles and starts, but when I try to open a page, containing an image and it should be loaded from new PostgreSQL database, the following error occurs:

Caused by: org.postgresql.util.PSQLException: Bad value of type long : \xffd8ffe000104a46494600010200000100010000ffdb004300...
at org.postgresql.jdbc2.AbstractJdbc2ResultSet.toLong(AbstractJdbc2ResultSet.java:2971)
at org.postgresql.jdbc2.AbstractJdbc2ResultSet.getLong(AbstractJdbc2ResultSet.java:2163)
at org.postgresql.jdbc2.AbstractJdbc2ResultSet.getBlob(AbstractJdbc2ResultSet.java:378)
at org.postgresql.jdbc2.AbstractJdbc2ResultSet.getBlob(AbstractJdbc2ResultSet.java:366)
at org.jboss.resource.adapter.jdbc.WrappedResultSet.getBlob(WrappedResultSet.java:386)
at org.hibernate.type.BlobType.get(BlobType.java:80)
at org.hibernate.type.BlobType.nullSafeGet(BlobType.java:134)
at org.hibernate.type.AbstractType.hydrate(AbstractType.java:105)
at org.hibernate.persister.entity.AbstractEntityPersister.hydrate(AbstractEntityPersister.java:2124)
at org.hibernate.loader.Loader.loadFromResultSet(Loader.java:1404)
at org.hibernate.loader.Loader.instanceNotYetLoaded(Loader.java:1332)
at org.hibernate.loader.Loader.getRow(Loader.java:1230)
at org.hibernate.loader.Loader.getRowFromResultSet(Loader.java:603)
at org.hibernate.loader.Loader.doQuery(Loader.java:724)
at org.hibernate.loader.Loader.doQueryAndInitializeNonLazyCollections(Loader.java:259)
at org.hibernate.loader.Loader.loadCollectionBatch(Loader.java:2053)
... 99 more

So my question is: What is going wrong in this transition? I think it is something related to import of data or configuring of Hibernate to read correctly Postgres data columns ...

Thanks in advance!

ADDITIONAL INFO:

Here is Postgres database table definition for FILEDATA:

CREATE TABLE filedata
(
  id bigint NOT NULL,
  version integer,
  created timestamp with time zone,
  createdbymemberid bigint,
  modified timestamp with time zone,
  modifiedbymemberid bigint,
  filedata bytea,
  file_id bigint,
)
WITH (
  OIDS=FALSE
);

FINALLY FOUND THE SOLUTION: In order to import filedata from H2 database into PostgreSQL database you need to use PostgreSQL function decode(filedata-in-hex, 'hex'). Here is a sample import:

INSERT INTO PUBLIC.FILEDATA(ID, VERSION, CREATED, CREATEDBYMEMBERID, MODIFIED, MODIFIEDBYMEMBERID, FILEDATA, FILE_ID) VALUES
(174849, 0, TIMESTAMP '2013-02-11 14:47:57.743', 174833, NULL, NULL, decode('89504e470d0a1a0a0000000d494844520000007b00000050080600000039ac0a8a00000c1a4944415478daed5d095494d7151e136bb3b659baa5494c62dbc4d85a4dba9ee6a49bd6b4f5246dd29ec6a5ae803126261aad5b5ca24489bb6ca2800a0ac822288280ca22b8a251510165515059040541d661bbbddf9b19986146f9c1f90707df77ce3bc30c33ef9f79dfbbefdefbdebdf7d790c47d038d1c0249b684245b42922d21c99690644b48b22524d912926c0949b684245be2be203bb9289b3cd213e9d3c3c1f49ffd...', 'hex'), 174848);

After that import is correctly insert into database as bytea and you can load it correctly!

回答1:

Resolved using PostgreSQL's function decode(). Answer and sample code can be found in question above :)

来源：https://stackoverflow.com/questions/15873848/transition-h2-data-to-postgresql

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hibernate

postgresql