What is the best way to store JSON data in Postgres? Is it possible to query a stored json string without using like/regex?
The best option is to use a column defined as jsonb.
And yes, Postgres has a lot of functions that let you query the content of a JSON value.
e.g. to check if a key/value pair is contained in the value json_column #> '{"key": "value"}'
Related
I need to construct complex query to json like "field name is Bob and field age less then 40 or salary more or equal 40000"
For patch json data I can use JsonPatch, but is there any format for filtering json data?
JSON Patch is used to perform partial update on json resources.
It seems like you are looking for ways to query a json resource.
For this you can use JsonPath which is a query language for JSON
I hope this helps anyone.
Is there a way to read a column of doctrine type "simply_array" or "array" in json?
My doctrine database is approached from another api and I want to read data from that api. However there is a column of type doctrine array that I want to convert into JSON.
I am unsure if there is a preferred way of doing this or I need to hack my way around it.
Here is an example of what is stored in the database as a doctrine array:
"a:1:{i:0;a:3:{s:3:\u0022day\u0022;i:5;s:4:\u0022time\u0022;s:7:\u0022morning\u0022;s:12:\u0022availability\u0022;N;}}"
That looks like the format of PHP's serialize() function. And the literal double-quotes in the string have been converted to unicode escape sequences.
You could do the following:
Fetch the serialized string
Fix the \u0022 sequences (replace them with ")
unserialize() it to reproduce the array
Convert the array to JSON with json_encode().
is it possible to change the resultset structure when retrieving data from elastic search?
the problem ist, the timeseries data are sometimes from 3000-8000 records which are a json array with json objects in it ... parsing it in this case not really efficient or necessary so i thought - could a resultset be transformed to just lets say a simple json object with an array of time and array of values? nothing more?
i could do this in java or php but since we want to have an efficent way of dealing with large datasets we are currently evaluating our options.
You can control what elasticsearch returns using source filtering:
https://www.elastic.co/guide/en/elasticsearch/reference/current/search-request-source-filtering.html
It can let you pick which part of the indexed document it will return, which, depending on your index structure could be an array of times and values, or at least, very easily mapped to it using the language of your choice.
Another possibility is to use scripting to control the results. If you map the result in this way, you should be able to get the hits object to be a JSON array of key: value.
I am trying with no success to insert a byte array in a postgresql json type as one of the json columns. is it possible? does anyone have an example?
You can't, at least natively. JSON only allows 3 basic primative data types: number, string, and boolean. Everything else must be serialized to a string or number.
This means that you have three basic options:
Serialize to hexadecimal. The advantage is that it becomes easy to turn into a bytea in PostgreSQL if you need it.
Serialize to base64. The advantage here is that it uses up less space.
Serialize to a number array. This is not preferred in my view since it is hard to constrain each number to between 0 and 255.
Are there any good UDFs in MySQL to deal with json data, that supports the ability to retrieve a particular value in json (by dot notation key - EG: json_get('foo.bar.baz')) as well as the ability to set the value of a particular key - EG: json_set('foo.bar.baz', 'value')?
I found http://www.mysqludf.org/lib_mysqludf_json/ - but it seems to only provide the ability to create json data structures from non-json column values, as opposed to interacting with json column values.
This UDF is able to parse JSON and return the value of an attribute:
https://github.com/kazuho/mysql_json
This other one too: https://github.com/webaroo/mysql-json-udf