Conquering jsonb in PostgreSQL

Recently PostgreSQL introduced the JSON and JSONB data types. At first, we ignored this news, we could not see how the JSON types could be of use to us. But then we used it once and then twice and then we almost went overboard with JSONs. This prompted us to stop, take a step back and analyze when a JSON type is useful and when it causes unnecessary hassle.

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1. CONQUERING
   JSONB IN
   POSTGRESQL
   Ines Panker
   

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2. Why did PostgreSQL add a
   JSON data type?
   

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3. Postgre SQL and NoSQL
   Postgre 9.4 (December 2014) JSONB: Binary format, slower input, faster processing
   JSON: Exact copy, same order
   Postgre 9.2
   No explicit
   schema
   Key-Value pairs in JSON are equal to
   Key-Value pairs in columns
   

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4. CREATE TABLE "PaymentRequest" (
   "ID" bigint PRIMARY KEY NOT NULL,
   "Created" timestamp without time zone,
   "LastEdited" timestamp without time zone,
   "Identifier" character varying(50),
   "FinalPrice" double precision,
   ...,
   "DeliveryTypeJSON" jsonb,
   "DeliveryAddressJSON" jsonb,
   "InvoiceAddressJSON" jsonb,
   "PromotionCodeJSON" jsonb,
   "PaymentJSON" jsonb);
   CREATE TABLE "PaymentRequestEntry" (
   "ID" bigint PRIMARY KEY NOT NULL,
   "CartCount" integer DEFAULT 0,
   "PriceWithTax" double precision,
   "FullPriceWithTax" double precision,
   "PriceNoTax" double precision,
   "FullPriceNoTax" double precision,
   ...,
   "ShopProductJSON" jsonb,
   "PaymentRequestID" integer DEFAULT 0,
   "VoucherID" integer DEFAULT 0
   );
   

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5. class ShopProduct{
   private function DataForInvoice() {
   $data = array(
   'SKU' => $this->SKU,
   'Title' => $this->LocaleTitle(),
   'Variant' => $this->Variant,
   'PriceWithTax' => $this->PriceWithTax(),
   'PriceNoTax' => $this->PriceNoTax(),
   'DiscountPriceWithTax'=> $this->PriceWithTax(true),
   'DiscountPriceNoTax' => $this->PriceNoTax(true),
   'Promotion' => $this->Promotion()->DataForInvoice(),
   'TaxRate' => $this->TaxRate($nice = false),
   'TaxPriceOfOne' => $this->TaxOfOneProduct(),
   'NoTax' => $this->NoTax(),
   'AllowOneStepTransaction' => $this->AllowOneStepTransaction,
   'IsVoucher' => $this->IsVoucher,
   ....
   );
   return $data;
   }
   }
   

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6. INSERT INTO "PaymentRequestEntry" VALUES (
   1,
   21.60,
   24.00,
   17.70,
   19.67,
   ...,
   '{
   "SKU":"LJCRD-24-ADL",
   "Title": "Visit Ljubljana Card, 24 hours",
   "Variant": "Adult",
   "PriceWithTax": 24.00,
   "PriceNoTax": 19.67,
   ...,
   "Promotion": {
   "Code": "SUMMER17",
   "DiscountPercent": 10.00,
   "DiscountAmount": null,
   "ActiveFrom": "2017-05-15 00:00:00"
   "ActiveTo": "2017-06-15 00:00:00"
   }
   "TaxRate": 0.22
   }',
   845623
   );
   ERROR: invalid input syntax for type json
   

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7. "ShopProductJSON"
   -----------------------------------------------
   {
   "SKU": "LJCRD-24-ADL",
   "NoTax": false,
   "Title": "Visit Ljubljana Card, 24 hours",
   "TaxRate": 0.22,
   "Variant": "Adult",
   "IsVoucher": false,
   "Promotion": {
   "Code": "SUMMER17",
   "ActiveTo": "2017-06-15 00:00:00",
   "ActiveFrom": "2017-05-15 00:00:00",
   "DiscountAmount": null,
   "DiscountPercent": "10.00"
   },
   "PriceNoTax": 19.67,
   "TaxRateNice": 0.22,
   "PriceWithTax": 24.00,
   "DiscountPriceNoTax": 17.70,
   "DiscountPriceWithTax": 21.60,
   "AllowOneStepTransaction": 1,
   ...
   }
   SELECT "ShopProductJSON" FROM "PaymentRequestEntry" WHERE "ID" = 1
   

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8. How to query??
   

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9. select
   "ID",
   "WholePriceWithTax",
   "NumberOfItems",
   "ShopProductJSON"->>'SKU' AS "SKU",
   "ShopProductJSON"->>'Title' as "Title",
   "ShopProductJSON"->>'PriceWithTax' as "PriceWithTax",
   "ShopProductJSON" from "PaymentRequestEntry"
   WHERE "PaymentRequestID" = 1
   ID
   WholePrice
   WithTax
   NumberOf
   Items SKU Title
   PriceWith
   Tax
   1 21.6 1 LJCRD-24-ADL
   Visit Ljubljana Card, 2
   4 hours
   24
   2 90 2 TOUR-BIKE-24 Bike tour of Ljubljana 45
   3 387 2 WC-17 WebCamp 2017 15
   

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10. How to query??
    (details)
    

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11. JSON Operators: ->
    arrays objects
    int text
    SELECT '["a",2,"3"]'::json->0 as data
    data (json)
    ------------------
    "a"
    SELECT '["a",2,"3"]'::json->1 as data
    data (json)
    ------------------
    2
    SELECT '["a",2,"3"]'::json->2 as data
    data (json)
    ------------------
    "3"
    SELECT '["a",2,"3"]'::json->'a' as data
    data (json)
    ------------------
    SELECT '{"a":1,"b":2}'::json->'b' as data
    data (json)
    ------------------
    2
    SELECT '{"a":1,"b":{"c":[1,2]}}'::json->'b'
    data (json)
    ------------------
    {"c":[1,2]}
    json json
    

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12. JSON Operators: ->>
    arrays
    int
    SELECT '["a",2,"3"]'::json->>0 as data
    data (text)
    ------------------
    "a"
    SELECT '["a",2,"3"]'::json->>1 > 1
    ERROR: operator does not exist: text >
    integer
    SELECT ('["a",2,"3"]'::json->>1)::int > 1
    data (boolean)
    ---------------
    t
    SELECT ('["a",2,"3"]'::json->1)::int > 1
    ERROR: cannot cast type json to integer
    text
    

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13. JSON Operators: ->>
    SELECT '{"a":1,"b":"word"}'::json->>'b'
    data (text)
    ------------------
    "word"
    SELECT '{"a":1,"b":"word"}'::json->>'b' = 'word'
    data(boolean)
    -----------
    t
    SELECT
    '{
    "identifier":1mo3j4,
    "items":[
    {
    "mon":"Monday",
    "tue":"Tuesday"
    },
    {
    "jan":"january",
    "feb":"february"
    }
    ]
    }'::json->'items'->0->>'tue'
    data (text)
    --------------
    "Tuesday"
    objects
    text text
    

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14. JSON Operators: #>, #>>
    SELECT
    '{
    "id":1,
    "items":[
    {
    "mon":"Monday",
    "tue":"Tuesday"
    },
    {
    "jan":"january",
    "feb":"february"
    }
    ]
    }'::json #>> '{items,0,tue}'
    data (text)
    --------------
    "Tuesday"
    SELECT
    '{
    "id":1,
    "items":[
    {
    "mon":"Monday",
    "tue":"Tuesday"
    },
    {
    "jan":"january",
    "feb":"february"
    }
    ]
    }'::json ->'items'->0->>'tue'
    data (text)
    --------------
    "Tuesday"
    objects
    array of text text
    

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15. JSONB Operators: @>, ?
    SELECT
    '{
    "promotion":
    {
    "code":"SUMMER17",
    "discount":"10"
    }
    }'::jsonb ? 'promotion'
    SELECT
    '{
    "promotion":
    {
    "code":"SUMMER17",
    "discount":"10"
    }
    }'::jsonb->'promotion' ? 'code'
    SELECT
    '{
    "id":1,
    "promotion":
    {
    "code":"SUMMER17",
    "discount":"10"
    }
    }'::jsonb @> '{"promotion":{"code":
    "SUMMER17"}}'
    data (boolean)
    --------------
    t
    objects
    text boolean
    objects
    jsonb boolean
    

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16. SELECT count("ID") as number_of_products_promo_was_used
    FROM "PaymentRequestEntry"
    WHERE "ShopProductJSON" @> '{"Promotion":{"Code": "SUMMER17"}}'
    {
    "SKU": "LJCRD-24-ADL",
    "IsVoucher": false,
    "Promotion": {
    "Code": "SUMMER17",
    },
    "PriceNoTax": "19.67",
    "TaxRateNice": "0.22",
    "PriceWithTax": "24.00",
    "DiscountPriceNoTax": "10.00",
    "DiscountPriceWithTax": "10.00",
    }
    SELECT
    "PaymentRequestID",
    sum(("ShopProductJSON"->>'PriceWithTax')::float)
    - sum(("ShopProductJSON"->>'DiscountPriceWithTax')::float) as money_saved
    FROM "PaymentRequestEntry"
    WHERE "ShopProductJSON" @> '{"Promotion":{"Code": "SUMMER17"}}‘
    GROUP BY "PaymentRequestID"
    PaymentRequestID money_saved
    845623 5.12
    845622 6.01
    845625 2.2
    ...
    

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17. SELECT
    SUM("CartCount") AS number_of_products,
    SUM(("ShopProductJSON"->>'PriceWithTax')::float) -
    SUM(("ShopProductJSON"->>'DiscountPriceWithTax')::float) AS
    money_saved,
    r."DeliveryAddressJSON"->>'Country' AS country
    FROM "PaymentRequestEntry" e
    INNER JOIN "PaymentRequest" r ON r."ID" = e."PaymentRequestID"
    WHERE "ShopProductJSON"->'Promotion'->>'Code' = 'SUMMER17'
    GROUP BY r."DeliveryAddressJSON"->>'Country'
    ORDER BY money_saved
    number_of_products money_saved country
    481 1503.72 DE
    512 1438.56 AT
    503 1289.05 IT
    ...
    

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18. SELECT
    sp."CalculatedPrice",
    e."ShopProductJSON"->>'PriceWithTax' as bought_price,
    e."Created"
    FROM "PaymentRequestEntry" e
    INNER JOIN "ShopProduct" sp
    ON sp."SKU" = e."ShopProductJSON"->>'SKU'
    AND e."ShopProductJSON" @> '{"SKU": "LJCRD-24-ADL"}'
    ORDER BY e."Created" desc
    CalculatedPrice bought_price Created
    24 24 2017-04-21 15:23:01
    24 21.6 2017-04-21 15:22:12
    ...
    24 22 2016-12-01 07:17:53
    ...
    

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19. EXPLAIN SELECT *
    FROM "PaymentRequestEntry"
    WHERE "ShopProductJSON" @> '{"Promotion":{"Code": "SUMMER17"}}'
    Seq Scan on "PaymentRequestEntry" (cost=0.00..21.02 rows=3 width=100)
    Filter: ((("ShopProductJSON" -> 'Promotion'::text) ->> 'Code'::text) =
    'SUMMER17'::text)
    GIN index
    over the
    WHOLE JSON
    for only 1 key
    in the JSON
    jsonb_ops :
    bigger & more
    versatily
    jsonb_path_ops:
    smaller & supports
    only @> querys
    

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20. EXPLAIN SELECT * FROM "PaymentRequestEntry"
    WHERE "ShopProductJSON" @> '{"Promotion":{"Code": "SUMMER17"}}'
    Seq Scan on "PaymentRequestEntry" (cost=0.00..511091.51 rows=3662
    width=85)
    table "PaymentRequestEntry" size: 3635 MB, 2.807.147 rows
    CREATE index json_index ON "PaymentRequestEntry"
    USING GIN (("ShopProductJSON"->'Promotion'->'Code'))
    CREATE index json_index ON "PaymentRequestEntry"
    USING GIN ("ShopProductJSON")
    @> ? ?| ?&
    CREATE index json_index ON "PaymentRequestEntry"
    USING GIN ("ShopProductJSON" jsonb_path_ops)
    @>
    indexname num_rows index_size
    json_index_ops 2.807.147 10 MB
    json_index_path_ops 2.807.147 7.832 MB (-20%)
    json_index_column 2.807.147 3.112 MB (-70%)
    json_index_column_path 2.807.147 3.112 MB (-70%)
    1.
    2.
    3.
    

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21. What have we used JSON
    data types for so far?
    

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22. Shop++
    

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23. Change log
    

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24. JSON to Form
    {
    "type":"object",
    "title":"Comment",
    "properties":{
    "name":{
    "title":"Name",
    "type":"string"
    },
    "email":{
    "title":"Email",
    "type":"string",
    "pattern":"^\\S+@\\S+$",
    "description":"Email will be used for evil."
    },
    "comment":{
    "title":"Comment",
    "type":"string",
    "maxLength":20,
    "validationMessage":"Don't be greedy!"
    }
    },
    "required":[
    "name",
    "email",
    "comment"
    ]
    }
    

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25. Evet Recurence Rules
    

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26. REST API calls
    

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27. The End
    

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