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SQL Parser Component

The parser component is a lightweight SQL analyzer used to extract metadata and hints from SQL queries.

Functionality

  • Hint Extraction: Uses regular expressions to find and parse comments in the format /* ttl:60 file:user.go line:42 batch:10 */.
    • ttl: Cache duration in seconds (SELECT queries only).
    • file: Source file that issued the query.
    • line: Line number in the source file.
    • batch: Maximum batching window in milliseconds (write operations only).
  • Query Type Detection: Identifies whether a query is a SELECT, INSERT, UPDATE, or DELETE statement.
  • Cacheability Check: Determines if a query is eligible for caching (must be a SELECT query with a ttl > 0).
  • Write Operation Detection: Identifies INSERT, UPDATE, and DELETE operations for batching.
  • Batch Key Generation: Groups write operations by normalized query text for efficient batching.

Key Methods

IsCacheable() bool

Returns true if query can be cached (SELECT with TTL > 0).

IsWritable() bool

Returns true if query is a write operation (INSERT, UPDATE, or DELETE).

IsBatchable() bool

Returns true if write operation can be batched. A query is batchable if:

  • It's a write operation (INSERT, UPDATE, or DELETE)
  • It has a batch hint with batch:N > 0

Transaction state is tracked at the connection level - batching is disabled inside transactions.

GetBatchKey() string

Generates a key for grouping write operations for batching:

  • Returns the normalized query text (with hints stripped)
  • Identical queries batch together, regardless of hint differences
  • Different queries create separate batches
  • Parameter values are part of the key (different values = different batches)

Examples:

// These have the same batch key (hints stripped):
p1 := Parse("/* file:app.go line:42 batch:10 */ INSERT INTO users (name) VALUES ('alice')")
p2 := Parse("/* file:handler.go line:100 batch:10 */ INSERT INTO users (name) VALUES ('alice')")
p1.GetBatchKey() == p2.GetBatchKey() // true - both return "INSERT INTO users (name) VALUES ('alice')"

// These have different batch keys (different values):
p3 := Parse("/* batch:10 */ INSERT INTO users (name) VALUES ('alice')")
p4 := Parse("/* batch:10 */ INSERT INTO users (name) VALUES ('bob')")
p3.GetBatchKey() != p4.GetBatchKey() // true - different parameter values

See the Write Batching Component for details on how batch keys are used.

Implementation

The parser uses optimized regular expressions to extract information without the overhead of a full SQL grammar parser, ensuring minimal latency in the proxy hot path.

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