Expression 필터

Expression filter는 read, write, query operation에 적용할 수 있습니다. Server가 expression을 평가해 조건에 맞는 record만 반환하거나 수정합니다.

서버 요구사항

Expression filter를 사용하려면 Aerospike Server 5.2 이상이 필요합니다.

Import

from aerospike_py import exp, predicates

기본 사용

# 표현식 빌드: age >= 21
expr = exp.ge(exp.int_bin("age"), exp.int_val(21))

# policy 통해 어떤 operation 에서든 사용
record = client.get(key, policy={"filter_expression": expr})

Value Constructor

Function	설명
int_val(v)	64-bit integer
float_val(v)	64-bit float
string_val(v)	String
bool_val(v)	Boolean
blob_val(v)	Bytes
list_val(v)	List
map_val(v)	Map/dict
geo_val(v)	GeoJSON string
nil()	Nil
infinity()	Infinity (unbounded range)
wildcard()	Wildcard

Bin Accessor

Function	설명
int_bin(name)	Integer bin
float_bin(name)	Float bin
string_bin(name)	String bin
bool_bin(name)	Boolean bin
blob_bin(name)	Blob bin
list_bin(name)	List bin
map_bin(name)	Map bin
geo_bin(name)	Geospatial bin
hll_bin(name)	HyperLogLog bin
bin_exists(name)	bin 존재 시 True
bin_type(name)	bin particle type

Comparison

Function	Operator
eq(l, r)	==
ne(l, r)	!=
gt(l, r)	>
ge(l, r)	>=
lt(l, r)	<
le(l, r)	<=

Logic

Function	설명
and_(*exprs)	Logical AND
or_(*exprs)	Logical OR
not_(expr)	Logical NOT
xor_(*exprs)	Logical XOR

# age >= 18 AND active == true
exp.and_(
    exp.ge(exp.int_bin("age"), exp.int_val(18)),
    exp.eq(exp.bool_bin("active"), exp.bool_val(True)),
)

# NOT deleted
exp.not_(exp.eq(exp.bool_bin("deleted"), exp.bool_val(True)))

수치 연산

Function	설명
num_add, num_sub, num_mul, num_div	산술
num_mod, num_pow, num_log	modulo, power, log
num_abs, num_floor, num_ceil	absolute, floor, ceil
to_int, to_float	타입 변환
min_, max_	min/max

# (price * quantity) > 1000
exp.gt(
    exp.num_mul(exp.int_bin("price"), exp.int_bin("quantity")),
    exp.int_val(1000),
)

Record Metadata

Function	설명
key(exp_type)	primary key
key_exists()	metadata 에 key 저장되어 있는가?
set_name()	set 이름
record_size()	바이트 크기 (Server 7.0+)
last_update()	마지막 update (epoch 부터 ns)
since_update()	마지막 update 부터 ms
void_time()	expiration (epoch 부터 ns)
ttl()	TTL 초
is_tombstone()	tombstone record?
digest_modulo(mod)	digest modulo (sampling)

# 1시간 내 만료
exp.lt(exp.ttl(), exp.int_val(3600))

# record 의 ~10% sample
exp.eq(exp.digest_modulo(10), exp.int_val(0))

Pattern Matching

# Regex (flags=2 는 case insensitive)
exp.regex_compare("^alice.*", 2, exp.string_bin("name"))

# Geospatial: 원 안의 point
region = '{"type":"AeroCircle","coordinates":[[-122.0, 37.5], 1000]}'
exp.geo_compare(exp.geo_bin("location"), exp.geo_val(region))

변수와 제어 흐름

# Conditional
exp.cond(
    exp.lt(exp.int_bin("age"), exp.int_val(18)), exp.string_val("minor"),
    exp.lt(exp.int_bin("age"), exp.int_val(65)), exp.string_val("adult"),
    exp.string_val("senior"),
)

# Let binding
exp.let_(
    exp.def_("total", exp.num_mul(exp.int_bin("price"), exp.int_bin("qty"))),
    exp.gt(exp.var("total"), exp.int_val(1000)),
)

Operation 과 함께 사용

Get / Put

expr = exp.ge(exp.int_bin("age"), exp.int_val(21))

# Get: 매칭 없으면 FilteredOut raise
record = client.get(key, policy={"filter_expression": expr})

# Put: status == "active" 일 때만 update
expr = exp.eq(exp.string_bin("status"), exp.string_val("active"))
client.put(key, {"visits": 1}, policy={"filter_expression": expr})

Query

query = client.query("test", "demo")
query.where(predicates.between("age", 20, 50))

expr = exp.eq(exp.string_bin("region"), exp.string_val("US"))
records = query.results(policy={"filter_expression": expr})

Batch

expr = exp.ge(exp.int_bin("score"), exp.int_val(100))
ops = [{"op": aerospike.OPERATOR_READ, "bin": "score", "val": None}]
records = client.batch_operate(keys, ops, policy={"filter_expression": expr})

Integer Bitwise Operation

Function	설명
int_and(*exprs)	Bitwise AND
int_or(*exprs)	Bitwise OR
int_xor(*exprs)	Bitwise XOR
int_not(expr)	Bitwise NOT
int_lshift(value, shift)	Left shift
int_rshift(value, shift)	Logical right shift
int_arshift(value, shift)	Arithmetic right shift
int_count(expr)	bit count (popcount)
int_lscan(value, search)	MSB 부터 scan
int_rscan(value, search)	LSB 부터 scan

# flags 의 bit 3 가 set 되어 있는가
exp.ne(
    exp.int_and(exp.int_bin("flags"), exp.int_val(0x08)),
    exp.int_val(0),
)

# permissions 를 왼쪽으로 4 bit shift
exp.int_lshift(exp.int_bin("perms"), exp.int_val(4))

Type Constants

key() 와 bin_type() 과 함께 EXP_TYPE_* constant 사용:

Constant	Value	설명
exp.EXP_TYPE_NIL	0	Nil
exp.EXP_TYPE_BOOL	1	Boolean
exp.EXP_TYPE_INT	2	Integer
exp.EXP_TYPE_STRING	3	String
exp.EXP_TYPE_LIST	4	List
exp.EXP_TYPE_MAP	5	Map
exp.EXP_TYPE_BLOB	6	Blob (bytes)
exp.EXP_TYPE_FLOAT	7	Float
exp.EXP_TYPE_GEO	8	GeoJSON
exp.EXP_TYPE_HLL	9	HyperLogLog

# integer primary key 가져오기
exp.key(exp.EXP_TYPE_INT)

# "data" bin 이 list 인 record 필터
exp.eq(exp.bin_type("data"), exp.int_val(exp.EXP_TYPE_LIST))

실용 예제

# active premium user
expr = exp.and_(
    exp.eq(exp.bool_bin("active"), exp.bool_val(True)),
    exp.or_(
        exp.eq(exp.string_bin("tier"), exp.string_val("gold")),
        exp.eq(exp.string_bin("tier"), exp.string_val("platinum")),
    ),
    exp.ge(exp.int_bin("age"), exp.int_val(18)),
)
records = client.query("test", "users").results(policy={"filter_expression": expr})

# 1시간 내 만료되는 record
expr = exp.and_(
    exp.gt(exp.ttl(), exp.int_val(0)),
    exp.lt(exp.ttl(), exp.int_val(3600)),
)
expiring = client.query("test", "cache").results(policy={"filter_expression": expr})

# 고액 transaction
expr = exp.gt(
    exp.num_mul(exp.float_bin("amount"), exp.int_bin("quantity")),
    exp.float_val(10000.0),
)
records = client.query("test", "transactions").results(policy={"filter_expression": expr})