Hi All,
I am trying to find out if I can start using in deep hibernate for orm mapping within my organization.
I don't think we have very strange needs, only in some situations we need to do huge
eager loading in
structures similar to the one appended at the end. Its a master child structure where children do have
additional nested children levels.
Due to the structure of the posted tables we have developed a reasonably fast and not too resource
consuming loading method than makes one query per table, and later it makes a post-processing to
eagerly rebuild
the objects in memory.
Code:
select * from PLANET
order by PLANET_ID;
select * from SATELLITE
order by PLANET_ID, SATELLITE_ID;
select * from STAR
order by PLANET_ID, STAR_ID;
select * from CONTINENT
order by PLANET_ID, CONTINENT_ID;
select * from CONTINENT_REGION
order by PLANET_ID, CONTINENT_ID, REGION_ID;
select * from COUNTRY
order by PLANET_ID, CONTINENT_ID, COUNTRY_ID;
select * from COUNTY
order by PLANET_ID, CONTINENT_ID, COUNTRY_ID, COUNTY_ID;
select * from ROAD
order by PLANET_ID, CONTINENT_ID, COUNTRY_ID, COUNTY_ID, ROAD_ID;
in practice queries for "lower level" tables are loaded keeping same order as their master for foreign
keys and adding additional order for local keys.
As a result we get a set of recordsets that are all "lexicographically" ordered in an homogeneous
way with respect to their parent (if any).
This gives us the ability to fetch the data as follows (single pass)
Code:
run all queries at this point...
cycle p on PLANET {
// load planet fields...
cycle cnt on CONTINENT while cnt.CONTINENT_FK_PLANET = p.PLANET_PK {
// load continent fields...
cycle cnt_r on CONTINENT_REGION while cnt_r.CONTINENT_REGION_FK_CONTINENT = cnt.CONTINENT_PK {
// load continent_region fields...
}
cycle cntry on COUNTRY while cntry.COUNTRY_FK_CONTINENT = cnt.CONTINENT_PK {
// load country fields...
cycle cnty on COUNTY while cnty.COUNTY_FK_COUNTRY = cntry.COUNTRY_PK {
// load county fields...
cycle rd on ROAD while rd.ROAD_FK_COUNTY = cnty.COUNTY_PK {
// load road fields...
}
}
}
}
cycle sat on SATELLITE while sat.SATELLITE_FK_PLANET = p.PLANET_PK {
// load sat fields...
}
cycle str on STAR while str.STAR_FK_PLANET = p.PLANET_PK {
// load str fields...
}
}
close all queries at this point...
Is there any way to obtain something similar in hibernate, or some way to implement this behavior?
I would really be glad also to hack hibernate source code if this is necessary, maybe someone else
out there might take advantage of this.
Thanks for the support
Tomaso Tosolini
-------------------8<--------------------------------------
Code:
DROP TABLE "TOWN";
DROP TABLE "COUNTY";
DROP TABLE "CONTINENT_REGION";
DROP TABLE "COUNTRY";
DROP TABLE "STAR";
DROP TABLE "SATELLITE";
DROP TABLE "CONTINENT";
DROP TABLE "PLANET";
-- |||||||||||||||||||||||||||||||||||||||||||||| --
CREATE TABLE "PLANET"
(
"PLANET_ID" VARCHAR2(20 BYTE) NOT NULL,
"NAME" VARCHAR2(20 BYTE) NOT NULL,
CONSTRAINT "PLANET_PK" PRIMARY KEY ("PLANET_ID")
);
CREATE TABLE "CONTINENT"
(
"PLANET_ID" VARCHAR2(20 BYTE) NOT NULL,
"CONTINENT_ID" VARCHAR2(20 BYTE) NOT NULL,
"NAME" VARCHAR2(20 BYTE) NOT NULL,
CONSTRAINT "CONTINENT_PK" PRIMARY KEY ("PLANET_ID", "CONTINENT_ID"),
CONSTRAINT "CONTINENT_FK_PLANET" FOREIGN KEY ("PLANET_ID") REFERENCES "PLANET" ("PLANET_ID")
);
CREATE TABLE "SATELLITE"
(
"PLANET_ID" VARCHAR2(20 BYTE) NOT NULL,
"SATELLITE_ID" VARCHAR2(20 BYTE) NOT NULL,
"NAME" VARCHAR2(20 BYTE) NOT NULL,
CONSTRAINT "SATELLITE_PK" PRIMARY KEY ("PLANET_ID", "SATELLITE_ID"),
CONSTRAINT "SATELLITE_FK_PLANET" FOREIGN KEY ("PLANET_ID") REFERENCES "PLANET" ("PLANET_ID")
);
CREATE TABLE "STAR"
(
"PLANET_ID" VARCHAR2(20 BYTE) NOT NULL,
"STAR_ID" VARCHAR2(20 BYTE) NOT NULL,
"NAME" VARCHAR2(20 BYTE) NOT NULL,
CONSTRAINT "STAR_PK" PRIMARY KEY ("PLANET_ID", "STAR_ID"),
CONSTRAINT "STAR_FK_PLANET" FOREIGN KEY ("PLANET_ID") REFERENCES "PLANET" ("PLANET_ID")
);
CREATE TABLE "COUNTRY"
(
"PLANET_ID" VARCHAR2(20 BYTE) NOT NULL,
"CONTINENT_ID" VARCHAR2(20 BYTE) NOT NULL,
"COUNTRY_ID" VARCHAR2(20 BYTE) NOT NULL,
"NAME" VARCHAR2(20 BYTE) NOT NULL,
CONSTRAINT "COUNTRY_PK" PRIMARY KEY ("PLANET_ID", "CONTINENT_ID", "COUNTRY_ID"),
CONSTRAINT "COUNTRY_FK_CONTINENT" FOREIGN KEY ("PLANET_ID", "CONTINENT_ID") REFERENCES "CONTINENT" ("PLANET_ID", "CONTINENT_ID")
);
CREATE TABLE "CONTINENT_REGION"
(
"PLANET_ID" VARCHAR2(20 BYTE) NOT NULL,
"CONTINENT_ID" VARCHAR2(20 BYTE) NOT NULL,
"REGION_ID" VARCHAR2(20 BYTE) NOT NULL,
"NAME" VARCHAR2(20 BYTE) NOT NULL,
CONSTRAINT "CONTINENT_REGION_PK" PRIMARY KEY ("PLANET_ID", "CONTINENT_ID", "REGION_ID"),
CONSTRAINT "CONTINENT_REGION_FK_CONTINENT" FOREIGN KEY ("PLANET_ID", "CONTINENT_ID") REFERENCES "CONTINENT" ("PLANET_ID", "CONTINENT_ID")
);
CREATE TABLE "COUNTY"
(
"PLANET_ID" VARCHAR2(20 BYTE) NOT NULL,
"CONTINENT_ID" VARCHAR2(20 BYTE) NOT NULL,
"COUNTRY_ID" VARCHAR2(20 BYTE) NOT NULL,
"COUNTY_ID" VARCHAR2(20 BYTE) NOT NULL,
"NAME" VARCHAR2(20 BYTE) NOT NULL,
CONSTRAINT "COUNTY_PK" PRIMARY KEY ("PLANET_ID", "CONTINENT_ID", "COUNTRY_ID", "COUNTY_ID"),
CONSTRAINT "COUNTY_FK_COUNTRY" FOREIGN KEY ("PLANET_ID", "CONTINENT_ID", "COUNTRY_ID") REFERENCES "COUNTRY" ("PLANET_ID", "CONTINENT_ID", "COUNTRY_ID")
);
CREATE TABLE "ROAD"
(
"PLANET_ID" VARCHAR2(20 BYTE) NOT NULL,
"CONTINENT_ID" VARCHAR2(20 BYTE) NOT NULL,
"COUNTRY_ID" VARCHAR2(20 BYTE) NOT NULL,
"COUNTY_ID" VARCHAR2(20 BYTE) NOT NULL,
"ROAD_ID" VARCHAR2(20 BYTE) NOT NULL,
"NAME" VARCHAR2(20 BYTE) NOT NULL,
CONSTRAINT "ROAD_PK" PRIMARY KEY ("PLANET_ID", "CONTINENT_ID", "COUNTRY_ID", "COUNTY_ID", "ROAD_ID"),
CONSTRAINT "ROAD_FK_COUNTY" FOREIGN KEY ("PLANET_ID", "CONTINENT_ID", "COUNTRY_ID", "COUNTY_ID") REFERENCES "COUNTRY" ("PLANET_ID", "CONTINENT_ID", "COUNTRY_ID", "COUNTY_ID")
);
-------------------8<--------------------------------------
with RUBY syntax:
Code:
planet :has_many continents
planet :has_many satellites
planet :has_many stars (just saw it in Star Wars so it's true)
continent :has_many countries
continent :has_many continent_regions
country :has_many counties
county :has_many roads
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