Analysis:
When we skip level when path is found, it changes the state of the json
engine. This breaks the sequence for json_get_path_next() which is called at
the end to ensure json document is valid and leads to crash.
Fix:
Use json_scan_next() at the end to check if json document has correct
syntax (is valid).
Analysis: The JSON functions(JSON_ARRAY[OBJECT|ARRAY_APPEND|ARRAY_INSERT|INSERT|SET|REPLACE]) result is truncated when the function is called based on LONGTEXT field. The overflow occurs when computing the result length due to the LONGTEXT max length is same as uint32 max length. It lead to wrong result length.
Fix: Add static_cast<ulonglong> to avoid uint32 overflow and fix the arguments used.
Analysis: JSON_VALUE() returns "null" string instead of NULL pointer.
Fix: When the type is JSON_VALUE_NULL (which is also a scalar) set
null_value to true and return 0 instead of returning string.
Hybrid functions (IF, COALESCE, etc) did not preserve the JSON property
from their arguments. The same problem was repeatable for single row subselects.
The problem happened because the method Item::is_json_type() was inconsistently
implemented across the Item hierarchy. For example, Item_hybrid_func
and Item_singlerow_subselect did not override is_json_type().
Solution:
- Removing Item::is_json_type()
- Implementing specific JSON type handlers:
Type_handler_string_json
Type_handler_varchar_json
Type_handler_tiny_blob_json
Type_handler_blob_json
Type_handler_medium_blob_json
Type_handler_long_blob_json
- Reusing the existing data type infrastructure to pass JSON
type handlers across all item types, including classes Item_hybrid_func
and Item_singlerow_subselect. Note, these two classes themselves do not
need any changes!
- Extending the data type infrastructure so data types can inherit
their properties (e.g. aggregation rules) from their base data types.
E.g. VARCHAR/JSON acts as VARCHAR, LONGTEXT/JSON acts as LONGTEXT
when mixed to a non-JSON data type. This is done by:
- adding virtual method Type_handler::type_handler_base()
- adding a helper class Type_handler_pair
- refactoring Type_handler_hybrid_field_type methods
aggregate_for_result(), aggregate_for_min_max(),
aggregate_for_num_op() to use Type_handler_pair.
This change also fixes:
MDEV-27361 Hybrid functions with JSON arguments do not send format metadata
Also, adding mtr tests for JSON replication. It was not covered yet.
And the current patch changes the replication code slightly.
Revert "fix JSON_ARRAYAGG not to over-quote json in joins"
This removes 8711adb786 but keeps the test case.
A different fix is coming up.
Because args can be Item_field's that are later
replaced by Item_direct_view_ref to the actual field.
While Item_field preserved in orig_args will stay unfixed
with item->field==NULL and no metadata
use metadata (in particular is_json() property) of the original
argument item, even if the actual argument was later replaced
with an Item_temptable_field
