hoorf opened a new issue #12008:
URL: https://github.com/apache/shardingsphere/issues/12008
this find pk range method will invoke many times for
```
@Override
public String buildSplitByPrimaryKeyRangeSQL(final String tableName,
final String primaryKey) {
return String.format("SELECT MAX(%s) FROM (SELECT %s FROM %s WHERE
%s>=? limit ?) t", quote(primaryKey), quote(primaryKey), quote(tableName),
quote(primaryKey));
}
```
use in
```
private Collection<ScalingPosition<?>> getPositionByPrimaryKeyRange(final
JobContext jobContext, final DataSource dataSource, final
InventoryDumperConfiguration dumperConfig) {
Collection<ScalingPosition<?>> result = new ArrayList<>();
String sql =
ScalingSQLBuilderFactory.newInstance(jobContext.getJobConfig().getHandleConfig().getDatabaseType())
.buildSplitByPrimaryKeyRangeSQL(dumperConfig.getTableName(),
dumperConfig.getPrimaryKey());
try (Connection connection = dataSource.getConnection();
PreparedStatement ps = connection.prepareStatement(sql)) {
long beginId = 0;
for (int i = 0; i < Integer.MAX_VALUE; i++) {
ps.setLong(1, beginId);
ps.setLong(2,
jobContext.getJobConfig().getHandleConfig().getShardingSize());
try (ResultSet rs = ps.executeQuery()) {
rs.next();
long endId = rs.getLong(1);
if (endId == 0) {
break;
}
result.add(new PrimaryKeyPosition(beginId, endId));
beginId = endId + 1;
}
}
// fix empty table missing inventory task
if (0 == result.size()) {
result.add(new PrimaryKeyPosition(0, 0));
}
} catch (final SQLException ex) {
throw new PrepareFailedException(String.format("Split task for
table %s by primary key %s error", dumperConfig.getTableName(),
dumperConfig.getPrimaryKey()), ex);
}
return result;
}
```
the pk start from 0,if use `SnowFlake ` pk , useless invoke many times
optimize
- find `min` and `max` pk count the range
- support the pk like `O100440001` to `O100449999` string pk not int pk
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