[client-v2, jdbc-v2] Fix handling strings with special characters #2781

Description

This is original problem ClickHouse/ClickHouse#99015:

Changelog category (leave one):

• Bug Fix (user-visible misbehavior in an official stable release)

Changelog entry:

Named String query parameters containing literal tab (0x09) or newline (0x0a) bytes fail with BAD_QUERY_PARAMETER ("isn't parsed completely") when sent via the native TCP protocol.

Bug description

When a String named query parameter contains a literal tab or newline character, the server throws:

Value hello	world cannot be parsed as String for query parameter 'param_x'
because it isn't parsed completely: only 5 of 11 bytes was parsed: hello

Root cause

There is a format mismatch across three layers in the native TCP parameter path:

1. Settings::toNameToNameMap() (src/Core/Settings.cpp:8217) decodes the Field dump format to raw bytes via readQuoted — so a tab stored as \t in the dump becomes a literal 0x09 byte in query_parameters.

2. ReplaceQueryParameterVisitor::visitQueryParameter() (src/Interpreters/ReplaceQueryParameterVisitor.cpp:143) then passes this raw value to deserializeTextEscaped.

3. deserializeTextEscaped → readEscapedStringIntoImpl (src/IO/ReadHelpers.cpp:659) treats raw 0x09 (tab) and 0x0a (newline) as TSV field delimiters, stopping the parse early. The remaining bytes cause the !read_buffer.eof() check at line 151 to throw.

The same bug exists for the HTTP interface when the parameter value is URL-encoded as %09 or %0A.

Workaround

Double-escape the character on the client side — pass \\t (backslash + t) instead of a literal tab. The extra backslash survives the Field dump round-trip as a single backslash, giving deserializeTextEscaped the two-char \t sequence it expects.

Test

The test includes:

• A baseline (simple string, works)
• The \\t workaround (works)
• Two cases demonstrating the bug (tab and newline, currently fail with the error above)
• Two cases showing the expected behaviour after the fix (currently failing — these should pass once the server-side bug is fixed)