alamb commented on a change in pull request #9840:
URL: https://github.com/apache/arrow/pull/9840#discussion_r605120867
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File path: rust/datafusion/src/catalog/information_schema.rs
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@@ -221,3 +262,226 @@ impl InformationSchemaTablesBuilder {
MemTable::try_new(schema, vec![vec![batch]]).unwrap()
}
}
+
+/// Builds the `information_schema.COLUMNS` table row by row
+///
+/// Columns are based on
https://www.postgresql.org/docs/current/infoschema-columns.html
+struct InformationSchemaColumnsBuilder {
+ catalog_names: StringBuilder,
+ schema_names: StringBuilder,
+ table_names: StringBuilder,
+ column_names: StringBuilder,
+ ordinal_positions: UInt64Builder,
+ column_defaults: StringBuilder,
+ is_nullables: StringBuilder,
+ data_types: StringBuilder,
+ character_maximum_lengths: UInt64Builder,
+ character_octet_lengths: UInt64Builder,
+ numeric_precisions: UInt64Builder,
+ numeric_precision_radixes: UInt64Builder,
+ numeric_scales: UInt64Builder,
+ datetime_precisions: UInt64Builder,
+ interval_types: StringBuilder,
+}
+
+impl InformationSchemaColumnsBuilder {
+ fn new() -> Self {
+ // StringBuilder requires providing an initial capacity, so
+ // pick 10 here arbitrarily as this is not performance
+ // critical code and the number of tables is unavailable here.
+ let default_capacity = 10;
+ Self {
+ catalog_names: StringBuilder::new(default_capacity),
+ schema_names: StringBuilder::new(default_capacity),
+ table_names: StringBuilder::new(default_capacity),
+ column_names: StringBuilder::new(default_capacity),
+ ordinal_positions: UInt64Builder::new(default_capacity),
+ column_defaults: StringBuilder::new(default_capacity),
+ is_nullables: StringBuilder::new(default_capacity),
+ data_types: StringBuilder::new(default_capacity),
+ character_maximum_lengths: UInt64Builder::new(default_capacity),
+ character_octet_lengths: UInt64Builder::new(default_capacity),
+ numeric_precisions: UInt64Builder::new(default_capacity),
+ numeric_precision_radixes: UInt64Builder::new(default_capacity),
+ numeric_scales: UInt64Builder::new(default_capacity),
+ datetime_precisions: UInt64Builder::new(default_capacity),
+ interval_types: StringBuilder::new(default_capacity),
+ }
+ }
+
+ fn add_column(
+ &mut self,
+ catalog_name: impl AsRef<str>,
+ schema_name: impl AsRef<str>,
+ table_name: impl AsRef<str>,
+ column_name: impl AsRef<str>,
Review comment:
I can change it into just taking &str -- though I think in the case
since there is just one callsite there is likely to be just one version of the
code
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