This article compares two SQL counter queries, presenting a detailed MySQL version with CASE statements and variable counters alongside a concise PostgreSQL version using ROW_NUMBER, and includes an explanation of the differences and a brief author biography.
The article analyzes a slow PostgreSQL query that joins multiple tables to fetch flight numbers, compares several alternative query formulations with their execution plans, and presents a final solution using array aggregation to achieve sub‑millisecond performance despite existing indexes.
This article examines how to efficiently query PostgreSQL tables that store comma‑separated city names by comparing plain OR conditions, regular‑expression operators, and array‑based searches with GIN indexes, showing speed measurements and validation of result consistency.
The article demonstrates how to split a space‑separated "validperiods" column into separate begin, end, and price fields in PostgreSQL using string_to_array, to_timestamp, regexp_replace, and unnest to transform the data into a readable tabular format.
This article explains how to transform a non‑visible 0x03‑separated city string stored in a PostgreSQL table into a sorted array so that routes with the same set of cities can be grouped and counted efficiently.
Olery’s journey from a mixed MySQL‑MongoDB setup to a PostgreSQL‑centric architecture reveals the pitfalls of schema‑less storage, the criteria for a robust database, a three‑stage migration process, and measurable performance gains across its services.
This article explains how to count paid and unpaid orders per user‑product pair in PostgreSQL by aggregating order statuses into arrays, using a sub‑query with GROUP BY and a CASE expression to produce accurate payment success and total order counts.
This article explains how to leverage PostgreSQL's unnest and string_to_array functions to split a comma‑separated 'arrive' column and efficiently query for popular island destinations such as Maldives, Phuket, Bali, and others without writing complex regular expressions.
The article explains how to calculate the total number of possible flight‑hotel combinations for travel packages by defining a custom multiplicative aggregate function in PostgreSQL, provides the SQL code, demonstrates its usage with examples, and discusses its practical advantages for flexible grouping.
