Already six years ago, in #5783, we noticed that alternator/executor.cc
has grown too large. The previous patches added hundreds of more lines
to it to implement vector search, and it reached a whopping 7,000 lines
of code. This is too much.
This patch splits from executor.cc two major chunks:
1. The implementation of **read** requests - GetItem, BatchGetItem,
Query (base table, GSI/LSI, and vector-search), and Scan - was
moved to a new source file alternator/executor_read.cc.
The new file has 2,000 lines.
2. Moved 250 lines of template functions dealing with attribute paths
and maps of them to a new header file, attribute_path.hh.
These utilities are used for many different operations - various
read operations use them for ProjectionExpression, and UpdateItem
uses them for modifications to nested attributes, so we need the
new header file from both executor.cc and executor_read.cc
The remaining executor.cc is still pretty big, 5,000 lines, and
contains write operations (PutItem, UpdateItem, DeleteItem,
BatchWriteItem) as well as various table and other operations, and
also many utility functions used by many types of operations, so
we can later continue this refactoring effort.
Refs #5783
Signed-off-by: Nadav Har'El <nyh@scylladb.com>
