![]() ![]() Repeat the whole benchmark several times to avoid warmup penalty Benchmark codeĪs promised, this was the benchmark code used for this blog post: Do measure things yourself, and if you cannot reproduce a performance problem, then don’t necessarily touch perfectly sound logic just because a blog post told you so. While in this case, the improvement is worth it irrespective of actual measurements (because performance can hardly be worse, and readability actually improves), always be careful with such benchmark results. You can safely switch to this nice standard SQL syntax already now. ) is such a popular idiom, and 8% is quite the significant improvement, that I think PostgreSQL should fix this. I think this is a case where it’s worth looking into simple patterns of expressions in aggregate functions. ![]() In RDBMS that don’t have such a cache, optimisation time is more costly per query, so less can be expected. Db2, Oracle, SQL Server), in case of which the optimisation needs to be done only once per cached plan, and then the plan can be reused. ![]() There was a tendency of such optimisations being favoured by RDBMS that have an execution plan cache (e.g. In a previous blog post (which is probably outdated by now), I’ve shown a lot of these cases, where the optimisation decision doesn’t depend on any cost model and data sets and should always be done, ideally. But this isn’t always the case in the real world, where optimisers make tradeoffs between: In a perfect world, two provably equivalent SQL syntaxes also perform the same way. But still, the FILTER clause outperforms CASE clause usage. The optimiser doesn’t optimise this as well as it could). This blog presented detailed knowledge on how to convert the case of a string in PostgreSQL.So, indeed, the redundant predicate improved things (in a perfect world, it shouldn’t, but here we are. The INITCAP() transforms each word's first character/alphabet in a string to uppercase and the remaining letters/characters to lowercase. The UPPER() function converts all the string characters/letters to uppercase, while the LOWER() converts all characters in a string to lowercase. In PostgreSQL, the UPPER(), LOWER(), and INITCAP() functions are used for letter case conversion. The output certifies the working of the letter case functions. Let’s use the letter case functions in the article_title column: SELECT LOWER(article_title), UPPER(article_title), We have already created a table named articles_info, whose data is shown in the following snippet: The output proves the working of the INITCAP() function.Įxample 4: How to Use Letter case Functions on Table’s Data Let’s learn how the INITCAP() function works in PostgreSQL SELECT INITCAP('Hello, welcome, how are you') In the following code, a string is passed to the UPPER() let's see how it works: SELECT LOWER('Hello, WELCOME, how are you') Īll letters have been converted to lowercase successfully.Įxample 3: Converting String letters to Title Case In the following code, a string is passed to the UPPER() let's see how it works: SELECT UPPER('Hello, welcome, how are you') Īll letters have been converted to UPPER CASE successfully.Įxample 2: Converting String letters to Lowercase INITCAP(): this function transforms each word's first character/alphabet in a string to uppercase and the rest of the characters to lowercase.: SELECT INITCAP(col_name) FROM table_name Įxample 1: Converting String letters to Uppercase LOWER(): It converts all characters/letters in a string to lowercase. UPPER(): This function converts all string characters to uppercase. To convert the case of a string in Postgres, you must use one of the following functions: How Do I Convert the Case of a String in Postgres? This blog demonstrates how to convert the string’s letter case in Postgres via practical examples. The process of letter case functions is simple and straightforward. These built-in functions can easily transform the case of your strings according to your requirements. For this purpose, Postgres provides various built-in functions. In PostgreSQL, converting the case of a string is a useful technique that is used to format the strings into a specific case. ![]()
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