Json_writer had two separate code paths: add_unquoted_str() for
numbers/bool/null, and add_escaped_str() which added the surrounding
quotes itself for strings. Single_line_formatting_helper, which
buffers consecutive array/object elements to decide if they fit on
one line, assumed only strings could ever be buffered and always
wrapped the flushed values in quotes. As a result, arrays of numbers
(e.g. "depends_on_map_bits", "rec_per_key") were incorrectly rendered
with their elements quoted as strings.
Unify both paths into add_escaped_quoted_str(): the caller now hands
over bytes that are already in their final on-the-wire form. String
escaping (json_escape_to_string) writes its own surrounding quotes,
while numbers/bool/null are passed through unquoted, so the one-line
helper just concatenates the buffered payloads on flush instead of
adding quotes itself. A DBUG_ASSERT in add_escaped_quoted_str() now
checks that every payload is already a quoted string or a bare
number/bool/null token, so a caller that violates the contract trips
an assertion in debug builds instead of silently producing invalid
JSON.
Also:
- Fix Json_writer_array::add(ulonglong)/(size_t), which went through
add_ll() with a cast to longlong and corrupted large unsigned
values (e.g. ULLONG_MAX); route them through add_ull() instead.
- Fix mysql-test/include/opt_context_schema.inc: "subquery_runs" was
nested inside the preceding object instead of being a sibling
member, and "rec_per_key" items are now declared as "number" to
match the corrected output.
- Update recorded .result files for opt_trace, opt_context_*, and
subselect_mat_analyze_json to reflect numbers/booleans no longer
being quoted inside JSON arrays.
- Extend unittest/sql/my_json_writer-t.cc with coverage for arrays
of primitives: plain integers, mixed types, sizes, multi-line
arrays, values flushed before a nested object, strings that were
already escaped by the one-line buffer, and invalid utf8mb4 input
through add_str().
- Rewrite the "multi-line array of integers" test to actually
overflow the one-line buffer (9 seven-digit numbers instead of 7),
since the previous version fit on one line and never exercised the
element-per-line flush path it claimed to test.
- Drop the now-redundant single-argument add_escaped_quoted_str()
overload; all call sites already know their length.
- Update json_escape_to_string()'s doc comments (my_json_writer.h,
sql_json_lib.h) to state that it quotes its output, not just
escapes it.
This task loads the stats of the tables that are used in a query,
from the trace into the optimizer. This feature is controlled
by optimizer_replay_context, and points to an user defined variable name,
that has the context information.
The stats such as num_of_records present in the table, indexes if present,
their names, along with the average number of records_per_key
with in each index, cost of reading an index are loaded from the trace.
Additionally, stats from range analysis i.e. ranges, and the
corresponding number of records, along with their costs are also
loaded from the trace.
The trace context which is in JSON format is firstly set into the
user defined session variable, and this variable name is set to
optimizer_replay_context system variable.
Later, when a user issues a query, the contents of the json context is
parsed and an in memory representation is built using the class
Optimizer_context_replay. This class is then used by the optimizer
to update and save original values of the tables, indexes, and range stats
in the methods "set_statistics_for_table()" of sql_statistics.cc, and
"check_quick_select()" of opt_range.cc.
After the query gets finished, the statistics that were updated
in the optimizer are restored back to the saved original values.
The entry point for parsing the json structure is in
"mysql_execute_command()" of sql_parse.cc, and similarly exit point
i.e. to restore the saved stats of the optimizer is at the end
of the same method.
Two new warning/error messages are introduced:
ER_JSON_OPTIMIZER_REPLAY_CONTEXT_PARSE_FAILED, and
ER_JSON_OPTIMIZER_REPLAY_CONTEXT_MATCH_FAILED
Move classes Json_string, and Json_saved_parser_state from
opt_histogram_json.cc to the newly created file sql_json_lib.h
Additionally, make the function json_unescape_to_string public earlier
defined as static in opt_histogram_json.cc, by
adding the declaration in sql_json_lib.h
Needed this change so that, the classes and functions can be reused in
other pieces of the code.
