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docs: Fold typical_query.md to internals.md
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@ -39,9 +39,48 @@ interface to parse the statement and generate a bytecode program, a step
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called preparing a statement. When a statement is prepared, it can be executed
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using the `sqlite3_step()` function.
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To inspect the bytecode program for a SQL statement, you can use the
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`EXPLAIN` command in the shell. For our example SQL statement, the bytecode
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looks as follows:
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To illustrate the different components of Limbo, we can look at the sequence
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diagram of a query from the CLI to the bytecode virtual machine (VDBE):
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```mermaid
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sequenceDiagram
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participant main as cli/main
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participant Database as core/lib/Database
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participant Connection as core/lib/Connection
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participant Parser as sql/mod/Parser
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participant translate as translate/mod
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participant Statement as core/lib/Statement
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participant Program as vdbe/mod/Program
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main->>Database: open_file
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Database->>main: Connection
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main->>Connection: query(sql)
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Note left of Parser: Parser uses vendored sqlite3-parser
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Connection->>Parser: next()
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Note left of Parser: Passes the SQL query to Parser
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Parser->>Connection: Cmd::Stmt (ast/mod.rs)
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Note right of translate: Translates SQL statement into bytecode
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Connection->>translate:translate(stmt)
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translate->>Connection: Program
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Connection->>main: Ok(Some(Rows { Statement }))
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note right of main: a Statement with <br />a reference to Program is returned
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main->>Statement: step()
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Statement->>Program: step()
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Note left of Program: Program executes bytecode instructions<br />See https://www.sqlite.org/opcode.html
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Program->>Statement: StepResult
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Statement->>main: StepResult
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```
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To drill down into more specifics, we inspect the bytecode program for a SQL
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statement using the `EXPLAIN` command in the shell. For our example SQL
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statement, the bytecode looks as follows:
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```
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limbo> EXPLAIN SELECT 'hello, world';
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@ -67,6 +106,7 @@ constant `'hello, world'` to register `r[1]`. The `ResultRow` instruction
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produces a SQL query result using contents of `r[1]`. Finally, the
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program terminates with the `Halt` instruction.
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## Frontend
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### Parser
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@ -1,37 +0,0 @@
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The following sequence diagram shows the typical flow of a query from the CLI to the [VDBE](https://www.sqlite.org/opcode.html).
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```mermaid
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sequenceDiagram
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participant main as cli/main
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participant Database as core/lib/Database
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participant Connection as core/lib/Connection
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participant Parser as sql/mod/Parser
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participant translate as translate/mod
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participant Statement as core/lib/Statement
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participant Program as vdbe/mod/Program
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main->>Database: open_file
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Database->>main: Connection
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main->>Connection: query(sql)
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Note left of Parser: Parser uses vendored sqlite3-parser
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Connection->>Parser: next()
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Note left of Parser: Passes the SQL query to Parser
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Parser->>Connection: Cmd::Stmt (ast/mod.rs)
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Note right of translate: Translates SQL statement into bytecode
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Connection->>translate:translate(stmt)
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translate->>Connection: Program
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Connection->>main: Ok(Some(Rows { Statement }))
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note right of main: a Statement with <br />a reference to Program is returned
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main->>Statement: step()
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Statement->>Program: step()
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Note left of Program: Program executes bytecode instructions<br />See https://www.sqlite.org/opcode.html
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Program->>Statement: StepResult
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Statement->>main: StepResult
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```
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