Created
May 24, 2014 03:39
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8 byte pretty much unique ID generator
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"http://instagram-engineering.tumblr.com/post/10853187575/sharding-ids-at-instagram" | |
| epoch generator ids runLength shardId seqId| | |
epoch := '01-01-2014' asDateAndTime asUnixTime. "1388545200" | |
generator := [:seed1 :seed2 | | |
| id | | |
id := (DateAndTime now asUnixTime - epoch) bitShift: 64-41. | |
id := id bitOr: (seed1 bitShift: (64-41-13)). | |
id := id bitOr: seed2 ]. | |
shardId := 1. | |
seqId := 1. | |
ids := IdentitySet new. | |
runLength := 1000000. | |
Transcript | |
show: 'Consecutive sample of '; | |
show: runLength printString; | |
cr; | |
show: ( | |
Time millisecondsToRun: [ | |
runLength timesRepeat: [ | |
ids add: (generator value: shardId value: (seqId \\ 1024) ) ]]) printString,'ms'; | |
tab; | |
show: 'Unique IDs: ', ids size printString . |
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CREATE OR REPLACE FUNCTION insta5.next_id(OUT result bigint) AS $$ | |
DECLARE | |
our_epoch bigint := 1314220021721; | |
seq_id bigint; | |
now_millis bigint; | |
shard_id int := 5; | |
BEGIN | |
SELECT nextval('insta5.table_id_seq') %% 1024 INTO seq_id; | |
SELECT FLOOR(EXTRACT(EPOCH FROM clock_timestamp()) * 1000) INTO now_millis; | |
result := (now_millis - our_epoch) << 23; | |
result := result | (shard_id << 10); | |
result := result | (seq_id); | |
END; | |
$$ LANGUAGE PLPGSQL; |
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