Dual-mode design
1. Objective
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In order to meet the PG mode and the compatible Oracle mode, IVORYSQL designed two modes: PG and Oracle. And the schema can be specified at initdb time;
2. Function
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Initdb -m initialization requires judgment of different modes, among which oracle mode requires the execution of SQL statements postgres_oracle.bki. The default is Oracle compatibility mode, and the process is as follows:
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Startup: When starting, it determines whether it is an Oracle compatibility mode based on the initialization mode;
Description:
database_mode: Used to indicate initialization mode;
database_mode=DB_PG，PG mode, and cannot be switched;
database_mode=DB_ORACLE， oracle compatibility mode;