postgres oracle sql difference functionality - ghdrako/doc_snipets GitHub Wiki
- https://www.crunchydata.com/blog/oracle-to-postgres-post-migration-improvements
- https://github.com/ghdrako/doc_snipets/wiki/postgres-extension-orafce
- ora2pg
- code2pg https://github.com/societe‑generale/code2pg
| oracle | postgresql | desc |
|---|---|---|
to_number(col,'xxxxxxxxxxxxxxxx') |
SELECT ('x' || lpad(hex, 16, '0'))::bit(64)::bigint |
conv 16 znakow hex na number |
len(col_str) |
lenght(col_str) |
dlugosc stringu |
123 || 456 -> 123456 |
123 || 456 -> Error |
concatenation |
nvl(MY_FIELD,'N/A') |
coalesce(MY_FIELD,'N/A') |
default value |
is not equal to NULL |
is equal to NULL |
empty string |
upper(description) like '%DISCUSS%' |
description ilike '%DISCUSS%' |
case-insensitive like query |
substr(tag,20) |
substring(tag from 0 for 20) |
first 20 characters of the tag string |
automonous transaction |
unsupported | unsupported |
alter table test add c4 varchar2(10) default 'd1' not null; |
alter table test add c4 varchar(10) not null default 'd1'; |
add defalut column not null |
sysdate |
current_date |
current date |
ROWID |
ctid |
physical address of a table row |
alter table t add column c char(1); |
alter table t add c char(1); |
add column to table |
ALTER TABLE tbl_name ALTER COLUMN col_name TYPE integer USING (NULLIF(col_name, '')::integer); |
ALTER TABLE <table_name> MODIFY (<column_name> <new_Type>) |
modify column typ from text to integer |
ALTER TABLE tbl_name ALTER COLUMN col_name TYPE varchar (11), ALTER COLUMN col_name2 TYPE varchar (11),ALTER COLUMN col_name3 TYPE varchar (11); |
ALTER TABLE place MODIFY (street_name VARCHAR2(20), county VARCHAR2(20), city VARCHAR2(20)) |
modify multiple column typ/size |
create table t(id serial primary key); |
create sequence seq start with 1; create table t(id number primary key); insert into t(id) values(seq.NEXVAL); |
autoincrementacja |
STRING_AGG |
LISTAGG |
f. analityczna |
:: or function CAST selet '123':INTEGER;
|
selet cast('123' as number) from dual; |
rzutowanie typow |
LIMIT/OFFSET select * from t limit 10 ofset 5; |
ROWNUM lub `FETCH FIRST N ROWS ONLY' |
limitowanie wynikow zapytan |
ALTER TABLE table_name RENAME TO new_table_name; |
ALTER TABLE table_name RENAME TO new_table_name;' alter table ebk.jeden rename to temp_jeden;` |
rename table |
| SELECT ROWNUM, * FROM employees; | SELECT ROW_NUMBER() OVER () AS rownum, * FROM employees; | |
| brak | synonymes,hints | |
| status_zadluzenia varchar(4) NOT NULL DEFAULT 'OK'::character varying | status_zadluzenia varchar2(4) DEFAULT 'OK' NOT NULL | w oracle najpierw musi byc default a potem not null - jak odwrotie to blad |
- https://www.postgresql.org/docs/current/datatype.html
- https://docs.oracle.com/en/database/oracle/oracle-database/19/sqlrf/Data-Types.html
| Postgres | Oracle |
|---|---|
| boolean | NUMBER(1) 0/1 CHAR(1) T/F |
| bigint / int8 | int , number(18,0) |
| character varying(s) , | varchar2(s) ,character varying |
| bpchar(s),char(s) | char(s) |
| character(s) | char(s) character(s) |
| integer / int4 | int, number(9,0) |
| numeric / decimal / number | number |
| numeric(p,s) / decimal(p,s) / number(p,s) | number(p,s) |
| numeric(p) / decimal(p) / number(p) | number(p) |
| real | float |
| xml | xmltype |
-
w PostgreSQL typ danych char(n) jest w praktyce taki sam jak bpchar(n), ponieważ oba oznaczają ciąg znaków o stałej długości, który jest dopełniany spacjami z prawej strony. Różnica polega jedynie na wewnętrznej implementacji — bpchar to wewnętrzna nazwa typu używana w metadanych PostgreSQL.
-
Oracle ROWID format OOOOOO.FFF.BBBBBB.RRR ... - unikalny w skali bazy, określa fizyczna lokalizacje wiersza
-
ctid . unikalny tylko w tabeli - nie określa lokalizacji wiersza
PCTFREE - fillfactor
CREATE TABLE distributors (
did integer,
name varchar(40),
UNIQUE(name) WITH (fillfactor=70)
)
WITH (fillfactor=70);
ALTER TABLE pgbench_accounts SET (fillfactor = 90);
CREATE INDEX idx_100 on t_static (id) WITH (FILFACTOR=100);
Virtual Column in Oracle
CREATE TABLE employees (
id NUMBER,
first_name VARCHAR2(10),
salary NUMBER(9,2),
commission NUMBER(3),
salary2 NUMBER GENERATED ALWAYS AS
(ROUND(salary*(1+commission/100),2)) VIRTUAL
);
Postgres 12
CREATE TABLE employees (
id bigint,
first_name varchar(10),
salary double precision,
commission integer,
salary2 double precision generated always as
(ROUND((salary*(1+commission/100))::numeric,2)) STORED
);
Tabele w Oraclu z defaulta przechowywane sa z duzej litery a w postgres z malej.
Oracle pozwala na
SELECT * FROM test HAVING count(*) > 3 GROUP BY i;
In Oracle indexes on column not contain null values but in Postgres contain. To simulate use for postgres partia index that exclude null values and for oracle function Index where function convert null to something other and indexing.
PostgreSQL does not create indexes on foreign keys automatically!!!