AST struct name rewording #6642
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Signed-off-by: Andres Taylor <andres@planetscale.com>
…e SQLVal struct Signed-off-by: Andres Taylor <andres@planetscale.com>
To support parameterised queries, Vitess has a argumnet expression. This commit changes the AST used to represent these expressions. Before, the same struct was used for literal values and arguments; this change introduces a new struct used only for arguments. Signed-off-by: Andres Taylor <andres@planetscale.com>
Signed-off-by: Andres Taylor <andres@planetscale.com>
Signed-off-by: Andres Taylor <andres@planetscale.com>
Signed-off-by: Andres Taylor <andres@planetscale.com>
Signed-off-by: Andres Taylor <andres@planetscale.com>
harshit-gangal
approved these changes
Sep 1, 2020
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I've always found two things confusing with the Vitess AST - one is that the same struct is used for literals and for parameterised query arguments, and the other is that literal expressions are represented by a
SQLValstruct.I think which words we use makes a big difference for how understandable something is, so this PR tries to improve on the word choices around arguments and literals.
Literalexpressions are expressions that always evaluate to a fixed value.SQLValmakes you think that it's a value, and a value is a runtime thing, not something that exists in source code. In source code (even SQL), we usually represent these values with literals.I know that there is a historic reason why arguments and literals were represented using the same struct, but this issue has been resolved, so there was no good reason to keep them as one.