Creating a Real-Time User Profile Recommendation System with PostgreSQL (1)

Simulation Scenario

Solution 1: Wide Table Solution

create table t_tags_1(appid int, userid int8, tag1 boolean, tag2 boolean, ...... tag1000 boolean);  
create table t_tags_10(appid int, userid int8, tag9001 boolean, tag9002 boolean, ...... tag10000 boolean);

Solution 2: Array Solution

create table t_arr(appid int, userid int8, tags int2[]) with(parallel_workers=128);
create index idx_t_array_tags on t_arr using gin (tags) with (fastupdate=on, gin_pending_list_limit= 1024000000);
create index idx_t_arr_uid on t_arr(userid);
insert into t_arr select 1, 2000000000*random(),(select array_agg(10000*random()) from generate_series(1,10000));nohup pgbench -M prepared -n -r -f ./test.sql -P 1 -c 50 -j 50 -t 2000000 > ./arr.log 2>&1 &

Solution 3: Bit Solution 1

APPID, USERID, TAG bit stream
create table t_bit(appid int, userid int8, tags varbit) ; create index idx_t_bit_uid on t_bit(userid);
date;for ((i=1;i<=50;i++)); do psql -c "insert into t_bit select 1, 2000000000*random(), \
(select (string_agg(mod((2*random())::int,2)::text,''))::varbit from generate_series(1,10000)) tags \
from generate_series(1,2000000)" ; done; date
create or replace function randbit(int) returns varbit as 
select (string_agg(mod((2*random())::int,2)::text,''))::varbit from generate_series(1,$1);$$
language sql strict volatile;
create or replace function zerobit(int) returns varbit as
select (string_agg('0',''))::varbit from generate_series(1,$1);$$
language sql strict immutable;
update t_bit set tags=randbit(10000) where userid=:id;
do language plpgsql 
sql text;
bit1 varbit := randbit(10000);
bit2 varbit := randbit(10000);
bit3 varbit := randbit(10000);
zbit varbit := zerobit(10000);
set max_parallel_workers_per_gather =27;
sql := 'select * from t_bit where bitand(tags,'''||bit1::text||''')='''||bit1::text||''' and bitand(tags,'''||bit2::text||''')>bit''0'' and bitand(tags,'''||bit3::text||''')='''||zbit::text||'''';
raise notice '%', sql;
-- execute sql;

Solution 4: Bit Solution 2



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