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SQL.DB interface and Select() implementation (#9)
* sketch out sql pkg and SQLQueryDB interface * start POC test for SQL querying * implement Query. add examples to proof of concept test * clean up sql.TestQuery * increase lint timeout. might be slowed down by sqlite(?) * add some warning comments
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| Original file line number | Diff line number | Diff line change |
|---|---|---|
| @@ -0,0 +1,130 @@ | ||
| package sql | ||
|
|
||
| import ( | ||
| "database/sql" | ||
| "errors" | ||
| "time" | ||
|
|
||
| "github.com/Masterminds/squirrel" | ||
| bt "github.com/elh/bitempura" | ||
| ) | ||
|
|
||
| var _ DB = (*TableDB)(nil) | ||
|
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| // DB is a SQL-backed, SQL-queryable, bitemporal database. | ||
| // WARNING: WIP. this implementation is experimental. | ||
| type DB interface { | ||
| bt.DB | ||
| // Select executes a SQL query (as of optional valid and transaction times). | ||
| Select(query squirrel.SelectBuilder, opts ...bt.ReadOpt) (*sql.Rows, error) | ||
| } | ||
|
|
||
| // NewTableDB constructs a SQL-backed, SQL-queryable, bitemporal database connected to a specific underlying SQL table. | ||
| // WARNING: WIP. this implementation is experimental. | ||
| func NewTableDB(eq ExecerQueryer, table string, pkColumnName string) (DB, error) { | ||
| // TODO: support composite PK through a pkFn(key string) Key struct | ||
| return &TableDB{ | ||
| eq: eq, | ||
| table: table, | ||
| pkColumnName: pkColumnName, | ||
| }, nil | ||
| } | ||
|
|
||
| // TableDB is a SQL-backed, SQL-queryable, bitemporal database that is connected to a specific underlying SQL table. | ||
| type TableDB struct { | ||
| eq ExecerQueryer | ||
| table string | ||
| pkColumnName string | ||
| } | ||
|
|
||
| // Get data by key (as of optional valid and transaction times). | ||
| // WARNING: unimplemented | ||
| func (db *TableDB) Get(key string, opts ...bt.ReadOpt) (*bt.VersionedKV, error) { | ||
| // SELECT * | ||
| // FROM <table> | ||
| // WHERE | ||
| // <base table pk> = <key> AND | ||
| // __bt_tx_time_start <= <as_of_tx_time> AND | ||
| // (__bt_tx_time_end IS NULL OR __bt_tx_time_end > <as_of_tx_time>) AND | ||
| // __bt_valid_time_start <= <as_of_valid_time> AND | ||
| // (__bt_valid_time_end IS NULL OR __bt_valid_time_end > <as_of_valid_time>) | ||
| // LIMIT 1 | ||
| return nil, errors.New("unimplemented") | ||
| } | ||
|
|
||
| // List all data (as of optional valid and transaction times). | ||
| // WARNING: unimplemented | ||
| func (db *TableDB) List(opts ...bt.ReadOpt) ([]*bt.VersionedKV, error) { | ||
| // SELECT * | ||
| // FROM <table> | ||
| // WHERE | ||
| // <base table pk> = <key> AND | ||
| // __bt_tx_time_start <= <as_of_tx_time> AND | ||
| // (__bt_tx_time_end IS NULL OR __bt_tx_time_end > <as_of_tx_time>) AND | ||
| // __bt_valid_time_start <= <as_of_valid_time> AND | ||
| // (__bt_valid_time_end IS NULL OR __bt_valid_time_end > <as_of_valid_time>) | ||
| return nil, errors.New("unimplemented") | ||
| } | ||
|
|
||
| // Set stores value (with optional start and end valid time). | ||
| // WARNING: unimplemented | ||
| func (db *TableDB) Set(key string, value bt.Value, opts ...bt.WriteOpt) error { | ||
| // INSERT | ||
| // INTO <table> | ||
| // (<fields...>, __bt_tx_time_start, __bt_tx_time_end, __bt_valid_time_start, __bt_valid_time_end) | ||
| // VALUES | ||
| // (<values...>, <tx_time_start>, <tx_time_end>, <valid_time_start>, <valid_time_end>) | ||
| // | ||
| // select out the conflicting records based on the write opt times. update them and add new ones as needed | ||
| return errors.New("unimplemented") | ||
| } | ||
|
|
||
| // Delete removes value (with optional start and end valid time). | ||
| // WARNING: unimplemented | ||
| func (db *TableDB) Delete(key string, opts ...bt.WriteOpt) error { | ||
| // select out the conflicting records based on the write opt times. update them and add new ones as needed | ||
| return errors.New("unimplemented") | ||
| } | ||
|
|
||
| // History returns versions by descending end transaction time, descending end valid time | ||
| // WARNING: unimplemented | ||
| func (db *TableDB) History(key string) ([]*bt.VersionedKV, error) { | ||
| // SELECT * | ||
| // FROM <table> | ||
| // WHERE | ||
| // <base table pk> = <key> | ||
| return nil, errors.New("unimplemented") | ||
| } | ||
|
|
||
| // Select executes a SQL query (as of optional valid and transaction times). | ||
| func (db *TableDB) Select(b squirrel.SelectBuilder, opts ...bt.ReadOpt) (*sql.Rows, error) { | ||
| options := db.handleReadOpts(opts) | ||
|
|
||
| // add tx and valid time to query | ||
| b = b.Where(squirrel.LtOrEq{"__bt_tx_time_start": options.TxTime}) | ||
| b = b.Where(squirrel.Or{squirrel.Eq{"__bt_tx_time_end": nil}, squirrel.Gt{"__bt_tx_time_end": options.TxTime}}) | ||
| b = b.Where(squirrel.LtOrEq{"__bt_valid_time_start": options.ValidTime}) | ||
| b = b.Where(squirrel.Or{squirrel.Eq{"__bt_valid_time_end": nil}, squirrel.Gt{"__bt_valid_time_end": options.ValidTime}}) | ||
|
|
||
| return b.RunWith(db.eq).Query() | ||
| } | ||
|
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| func (db *TableDB) handleReadOpts(opts []bt.ReadOpt) *bt.ReadOptions { | ||
| now := time.Now() | ||
| options := &bt.ReadOptions{ | ||
| ValidTime: now, | ||
| TxTime: now, | ||
| } | ||
| for _, opt := range opts { | ||
| opt(options) | ||
| } | ||
|
|
||
| return options | ||
| } | ||
|
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| // ExecerQueryer can Exec or Query. Both sql.DB and sql.Tx satisfy this interface. | ||
| type ExecerQueryer interface { | ||
| Exec(query string, args ...interface{}) (sql.Result, error) | ||
| Query(query string, args ...interface{}) (*sql.Rows, error) | ||
| QueryRow(query string, args ...interface{}) *sql.Row | ||
| } |
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