Is there any solution to search by multiple string keys in the Couchbase?
For example I have an index:
emit(['example', doc.field1, doc.field2], doc.id);
And field1 and field2 are string variables.
I cannot use startkey and endkey because compound array index key is still treated as a string. So I have problem like this. But also I have string keys. So I cannot use Spatial Views.
Is there any solution other than a finding of multiple result sets for each part of the key, and then finding their intersection?
If you are limited to using views, then as you already discovered, there is no way to filter by independent fields.
If you are using (or can upgrade to) Couchbase 4.x, then you can do this with a simple N1QL query:
SELECT * FROM bucket WHERE field1 = 'bla' AND field2 ='blabla'
Be sure to create indexes on the two fields:
CREATE INDEX ix_field1 ON bucket(field1)
Related
I have the following query:
SELECT *
FROM table
WHERE (id, other_id, status)
IN (
(1, 'XYZ', 'OK'),
(2, 'ZXY', 'OK') -- , ...
);
Is it possible to construct this query in a type-safe manner using jOOQ, preferably without generating composite keys? Is it possible to do this using jOOQ 3.11?
My apologies, it seems my Google-fu was not up to par. The opposite of this question can be found here: Use JOOQ to do a delete specifying multiple columns in a "not in" clause
For completeness' sake, so that other Google searches might be more immediately helpful, the solution is:
// can be populated using DSL.row(...); for each entry
Collection<? extends Row3<Long, String, String>> values = ...
dslContext.selectFrom(TABLE)
.where(DSL.row(ID, OTHER_ID, STATUS).in(values))
.fetch();
Relevant jOOQ documentation: https://www.jooq.org/doc/3.14/manual/sql-building/conditional-expressions/in-predicate-degree-n/
Your own answer already shows how to do this with a 1:1 translation from SQL to jOOQ using the IN predicate for degrees > 1.
Starting from jOOQ 3.14, there is also the option of using the new <embeddablePrimaryKeys/> flag in the code generator, which will produce embeddable types for all primary keys (and foreign keys referencing them). This will help never forget a key column on these queries, which is especially useful for joins.
Your query would look like this:
ctx.selectFrom(TABLE)
.where(TABLE.PK_NAME.in(
new PkNameRecord(1, "XYZ", "OK"),
new PkNameRecord(2, "ZXY", "OK")))
.fetch();
The query generated behind the scenes is the same as yours, using the 3 constraint columns for the predicate. If you add or remove a constraint from the key, the query will no longer compile. A join would look like this:
ctx.select()
.from(TABLE)
.join(OTHER_TABLE)
.on(TABLE.PK_NAME.eq(OTHER_TABLE.FK_NAME))
.fetch();
Or an implicit join would look like this:
ctx.select(OTHER_TABLE.table().fields(), OTHER_TABLE.fields())
.from(OTHER_TABLE)
.fetch();
I have a table in my database which stores a list of string values as a jsonb field.
create table rabbits_json (
rabbit_id bigserial primary key,
name text,
info jsonb not null
);
insert into rabbits_json (name, info) values
('Henry','["lettuce","carrots"]'),
('Herald','["carrots","zucchini"]'),
('Helen','["lettuce","cheese"]');
I want to filter my rows checking if info contains a given value.
In SQL, I would use ? operator:
select * from rabbits_json where info ? 'carrots';
If my googling skills are fine today, I believe that this is not implemented yet in JOOQ:
https://github.com/jOOQ/jOOQ/issues/9997
How can I use a native predicate in my query to write an equivalent query in JOOQ?
For anything that's not supported natively in jOOQ, you should use plain SQL templating, e.g.
Condition condition = DSL.condition("{0} ? {1}", RABBITS_JSON.INFO, DSL.val("carrots"));
Unfortunately, in this specific case, you will run into this issue here. With JDBC PreparedStatement, you still cannot use ? for other usages than bind variables. As a workaround, you can:
Use Settings.statementType == STATIC_STATEMENT to prevent using a PreparedStatement in this case
Use the jsonb_exists_any function (not indexable) instead of ?, see https://stackoverflow.com/a/38370973/521799
How could I query a levelDB database by values in nodejs?
I have key: value pairs in my leveldb database and I want to search some values in it and find that key-value pair from that result. I am a beginner in leveldb.
{
"key1" : {
"data1": "value1",
"data2": "value2",
"data3": "value3"
}
}
So, I want to query value where data3 == value3 and get that key-value pair.
In levelDB, we can only get data on the basis of key.
Is there any other alternative?
In leveldb, which a low level database abstraction you can "only" query by exact key match or prefix key range.
You can not query by value without somekind duplication.
What pattern I adopted in my graphdb project is to follow the EAV model with a secondary "table" to store the index.
In Python plyvel you can emulate "table" using prefixed databases. Or see how FoundationDB does it in its Subspace implementation. Basically, every key-value pair of a given "table" or "space" is prefixed with a particular bytes sequence, that is all.
The first table, looks like the following:
(Entity, Attribute) → (Value)
Where Entity is a (random) identifier and Attribute is the byte representation of field name and last but not least Value is the bytes serialized value associated with Attribute for the given Entity.
The table schema is done that way so that you can quickly fetch using a range query all Attribute and Value using prefix range search over a given Entity.
The index table use the following schema:
(Attribute, Value) → Entity
That is it a shuffled version of the first table.
This is done like so, to make it possible to quickly fetch Entity that match a particular Attribute == Value that's what you are looking for.
There is alternative implementations for what you are looking for. Lookup my answers about leveldb and key-value stores e.g. Expressing multiple columns in berkeley db in python?
Good luck!
I am having difficulties with Waterline models and creating the Postgres tables related to those models.
No matter what I do to create a varchar(n) in the table through a model, it converts the attribute to text. And bigint also is being converted to integer!
Should I change the ORM?
Is there a way to do that?
You can do a more pleasant approach, using Waterline to "RUD" in "CRUD" but not to "C" - create! This because Waterline can be very "bad" at creating intermediary tables, primary keys (composite keys) and etc. So what I do today is this:
Compose a full .sql file archive to create indexes and tables.
Create the database once. (Alter if needed).
Declare all the tables as models. Just insert the type, primary key (if it is a single one) and lifecycle callbacks.
Make sure that config/models.js is set to migrate : safe.
Conclusion: I can insert, read and delete rows with Waterline, but I don't trust it (performance-wise) to create my tables. Sequelize on the other hand is a much more mature ORM and can be used if you need it. For me the hybrid waterline + SQL is sufficient.
EDIT: My models dont have any aggregation (like my_pets: { model: pet} ), just row names and types, as simple as possible.
Sails supported datatype:
String, text, integer, float, date, datetime, boolean, binary, array, json, mediumtext, longtext, objectid
If you need to specify exact length -> varchar(n), you need to use supported data type as shown above, or sails provide option called query.
Model.query() method which you can use to perform any kind of query you want.
var queryString='CREATE TABLE if not exists sailsusers.test (id INT NOT NULL,name VARCHAR(45) NULL,PRIMARY KEY (id))'
Test.query(queryString,function(err,a){
if(err)
return console.log(err);
console.log(a,'\n',b);
res.ok();
});
I am very new to Cassandra and this time still I have not done my part on reading much about the architecture. I have a simple question for which I am not getting an answer for.
This is a sample data when I do a list abcColumnFamily:
RowKey:Message_1
=> (column=word, value=Message_1, timestamp=1373976339934001)
RowKey:Message_2
=> (column=word, value=Message_2, timestamp=1373976339934001)
How can I search for the Rowkey having say Message_1
In SQL world: Select * from Table where Rowkey = 'Message_1' (= OR like). I want to simply search on full string.
My intention is to just check whether a particular data of my interest is there in a rowkey or not.
For CQL try:
select * from abcColumnFamily where KEY = 'Message_1'
If You want to query that data using CLI try the following:
assume abcColumnFamily keys as utf8;
get abcColumnFamily['Message_1'];