Why SQLite Uses Bytecode
sqlite.org
Why SQLite Uses Bytecode
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Re: Why SQLite Uses Bytecode
#2SQLite's design docs were the first time I had seen a database use a virtual machine instead of walking a tree. I later noticed VMs in libraries, embedded DSLs, and other applications outside of large general-purpose programming languages. That really drove home for me that VMs could be anywhere and were often a useful step in handling a user's expressions.
Re: Why SQLite Uses Bytecode
#3SQLite's design docs were the first time I had seen a database use a virtual machine instead of walking a tree. I later noticed VMs in libraries, embedded DSLs, and other applications outside of large general-purpose programming languages. That really drove home for me that VMs could be anywhere and were often a useful step in handling a user's expressions.
SQLite is the first one I’ve looked at the internals of. Do others walk an AST of the query instead?
Re: Why SQLite Uses Bytecode
#4SQLite's design docs were the first time I had seen a database use a virtual machine instead of walking a tree. I later noticed VMs in libraries, embedded DSLs, and other applications outside of large general-purpose programming languages. That really drove home for me that VMs could be anywhere and were often a useful step in handling a user's expressions.
SQLite is the first one I’ve looked at the internals of. Do others walk an AST of the query instead?
Yes, postgres for example. It maps pretty close to what you see from `explain` where the ops are pretty high level, reducing interpreter overhead. JIT's big gain is speeding up reading values out of row data
Re: Why SQLite Uses Bytecode
#5SQLite's design docs were the first time I had seen a database use a virtual machine instead of walking a tree. I later noticed VMs in libraries, embedded DSLs, and other applications outside of large general-purpose programming languages. That really drove home for me that VMs could be anywhere and were often a useful step in handling a user's expressions.
SQLite is the first one I’ve looked at the internals of. Do others walk an AST of the query instead?
FTA:
> Tree-Of-Objects → The input SQL is translated in a tree of objects that represent the processing to be done. The SQL is executed by walking this tree. This is the technique used by MySQL and PostgreSQL.
Re: Why SQLite Uses Bytecode
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Re: Why SQLite Uses Bytecode
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Re: Why SQLite Uses Bytecode
#8The problem of rendering a tree-of-objects as a table is sufficiently difficult that nobody does it, as far as I know. Hence, no tree-of-objects database engine provides the level of detail in their "EXPLAIN" output that SQLite provides.
I believe Microsoft SQL Server uses an object tree internally, and yet its query plan output is a table:
https://learn.microsoft.com/en-us/sql/t-sql/statements/set-s...
Re: Why SQLite Uses Bytecode
#9SQLite's design docs were the first time I had seen a database use a virtual machine instead of walking a tree. I later noticed VMs in libraries, embedded DSLs, and other applications outside of large general-purpose programming languages. That really drove home for me that VMs could be anywhere and were often a useful step in handling a user's expressions.
SQLite is the first one I’ve looked at the internals of. Do others walk an AST of the query instead?
Sorry, I’d read the article a couple years ago and forgot he goes into depth on the other approaches. My bad.
Re: Why SQLite Uses Bytecode
#10SQLite's design docs were the first time I had seen a database use a virtual machine instead of walking a tree. I later noticed VMs in libraries, embedded DSLs, and other applications outside of large general-purpose programming languages. That really drove home for me that VMs could be anywhere and were often a useful step in handling a user's expressions.
Everything is either a compiler or interpreter