Help Center/ GaussDB/ Service Overview/ Compatibility with Oracle/ Primary/Standby Instances/ Pseudocolumns
Updated on 2024-05-14 GMT+08:00
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Pseudocolumns

GaussDB is compatible with hierarchical query pseudocolumns, sequence pseudocolumns, and rownum pseudocolumns. Other pseudocolumns are not supported.

Hierarchical Query Pseudocolumns

Table 1 Hierarchical query pseudocolumns

No.

Oracle

GaussDB

1

connect_by_iscycle

Supported.

2

connect_by_isleaf

Supported.

3

LEVEL pseudocolumn

Supported.

Sequence Pseudocolumns

Table 2 Sequences

No.

Oracle

GaussDB

Difference

1

currval

Supported, with differences.

It is implemented as a function in GaussDB. The call mode is compatible with Oracle.

2

nextval

Supported, with differences.

It is implemented as a function in GaussDB. The call mode is compatible with Oracle.

ROWNUM Pseudocolumn

Table 3 rownum

No.

Oracle

GaussDB

Difference

1

rownum

Supported, with differences.

When Oracle uses rownum in the left, right, and full join conditions for filtering, the performance varies according to the conditions. The rownum condition may be ignored or partially ignored. However, GaussDB filters the results after left, right, and full join.