Most of the analysis of the WHERE clause is done in statement_restrictions. It determines
what parts to use for the primary or secondary index, and what parts to use for filtering.
The difficult part is that it has a very wide interface. After construction, the user must pick
the correct bits from many public functions. There are subtle interactions between them
that are hard to untangle.
This series simplifies the interface as it is used for selection filtering. In the end, only
two public functions are used, both returning expressions: one for the partition-level
filtering, one for the clustering row level filtering.
In the end, the WHERE clause is factored into three parts:
- one part goes into the read_command of the primary or secondary index
- another part (that references only partition key columns and static key columns) is used to filter entire partitions
- another part (that currently references only clustering key columns and regular columns, but one day may reference other columns) is used to filter clustering rows
Refactoring, no backport.
Closesscylladb/scylladb#20487
* github.com:scylladb/scylladb:
cql3: statement_restrictions: drop accessors for single-column key restrictions
cql3: selection: adjust indentation
cql3: selection: delete empty loop
cql3: statement_restrictions, selection: fold multi-column restrictions into row-level filter
cql3: statement_restrictions, selection: merge clustering key filter and regular columns filter
cql3: statement_restrictions, selection: merge partition key filter and static columns filter
cql3: selection: filter regular and static rows as a single expression each
cql3: statement_restrictions: collect regular column and static column filters into single expressions
cql3: selection: filter clustering key as a single expression
cql3: statement_restrictions: expose filter for clustering key
cql3: selection: filter partition key as a single expression
cql3: statement_restrictions: expose filter for partition key
cql3: statement_restrictions: remove relations used for indexing from filtering
cql3: statement_restrictions: bail out of find_idx if !_uses_secondary_index
cql3: statement_restrictions, modification_statement: pass correct value of check_indexes
cql3: statement_restrictions: correct mismatched clustering/partition restrictions references
cql3: statement_restrictions: precalculate get_column_defs_for_filtering()
cql3: selection: do_filter(): push static/regular row glue to higher level
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