Library Version 11.2.5.3

Library Version 12.1.6.1

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Specifying a Berkeley DB schema using SQL DDL			Specifying a Berkeley DB schema + using SQL DDL
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Specifying a Berkeley DB schema using SQL DDL

Specifying a Berkeley DB schema + using SQL DDL

- When starting a new Berkeley DB project, much of the code that you - must write is dedicated to defining the BDB environment: what - databases it contains, the types of the databases, and so forth. - Also, since records in BDB are just byte arrays, you must write - code that assembles and interprets these byte arrays. +

+ When starting a new Berkeley DB project, much of the code + that you must write is dedicated to defining the BDB + environment: what databases it contains, the types of the + databases, and so forth. Also, since records in BDB are just + byte arrays, you must write code that assembles and interprets + these byte arrays.

- Much of this code can be written automatically (in C) by the - db_sql_codegen utility. To use it, you first specify the schema of your Berkeley - DB environment in SQL Data Definition Language (DDL). Then you - invoke the db_sql_codegen command, giving the DDL as input. - db_sql_codegen reads the DDL, and writes C code that - implements a storage-layer API suggested by the DDL. +

+ Much of this code can be written automatically (in C) by + the db_sql_codegen utility. To use it, you first specify the + schema of your Berkeley DB environment in SQL Data Definition + Language (DDL). Then you invoke the db_sql_codegen command, + giving the DDL as input. db_sql_codegen + reads the DDL, and writes C code that implements a + storage-layer API suggested by the DDL.

The generated API includes a general-purpose initialization - function, which sets up the environment and the databases (creating - them if they don't already exist). It also includes C structure - declarations for each record type, and numerous specialized - functions for storing and retrieving those records. + function, which sets up the environment and the databases + (creating them if they don't already exist). It also includes + C structure declarations for each record type, and numerous + specialized functions for storing and retrieving those + records.

- db_sql_codegen can also produce a simple test program - that exercises the generated API. This program is useful as an - example of how to use the API. It contains calls to all of the - interface functions, along with commentary explaining what the code - is doing. + db_sql_codegen can also produce a simple + test program that exercises the generated API. This program is + useful as an example of how to use the API. It contains calls + to all of the interface functions, along with commentary + explaining what the code is doing.

- Once the storage layer API is produced, your application may use it - as is, or you may customize it as much as you like by editing the - generated source code. Be warned, however: - db_sql_codegen is a one-way process; there is no way to - automatically incorporate customizations into newly generated code, - if you decide to run db_sql_codegen again. +

+ Once the storage layer API is produced, your application + may use it as is, or you may customize it as much as you like + by editing the generated source code. Be warned, however: + db_sql_codegen is a one-way process; + there is no way to automatically incorporate customizations + into newly generated code, if you decide to run + db_sql_codegen again.

- To learn more about db_sql_codegen, please consult the - db_sql_codegen utility manual page in the Berkeley DB C API Reference Guide. + To learn more about db_sql_codegen, + please consult the db_sql_codegen utility manual page in the + Berkeley DB C API Reference Guide.

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