Language syntax changes all the time. Their point is that sql syntax is a mess and can be cleaned up.
Maybe not, just as we don't call "rank() OVER" SQL. We call it SQL:2003. Seems we're calling this GoogleSQL. But perhaps, in both cases, we can use SQL for short?
EssGyooGell: A Modest Proposal
I really like this idea of piping SQL queries rather than trying to create the perfect syntax from the get go.
+1 for readability too.
In order for a thing to be considered legacy, there needs to be a widespread successor available.
SQL might have been invented in the 70s but it's still going strong as no real alternative has been widely adopted so far - I'd wager that you will find SQL at most software companies today.
Calling it legacy is not realistic IMO.
We would invent the underlying engines for sure but not the language on top of it. It doesn't map at all to how it's actually used by programmers. SQL is the JS to WebAssembly, being able to write the query plan directly via whatever language or mechanism you prefer would be goated.
It has to be my biggest pain point dealing with SQL, having to hint to the optimizer or write meta-SQL to get it to generate the query plan I already know I want dammit! is unbelievably frustrating.
I don't think that definition of legacy is useful because so many things which hardly anyone calls "legacy" fit the definition - for example: Javascript as the web standard, cars in cities and bipartisan democracy.
I think many of us would say that that none of these is an ideal solution for the problem being solved, but it's what we are stuck with and I cannot think anyone could call it "legacy systems" until a viable successor is widespread.
> having to hint to the optimizer or write meta-SQL to get it to generate the query plan I already know I want dammit'
That's not in the domain of SQL. If you're not getting the most optimized query plan, there is something wrong with the DBMS engine or statistics -- SQL, the language, isn't supposed to care about those details.
That's my point, I think we've reached the point where SQL the langage can be more of a hindrance than help because in a lot of cases we're writing directly to the engine but with oven mitts on. If I could build the query from the tree with scan, filter, index scan, cond, merge join as my primitives it would be so nice.
Not sure if this is an attempt to simplify things or an oversight, but favoring convenience (no need to remember multiple keywords) over explicitness (but the keywords have different meanings) tends to cause problems, in my observation.
To me that feels as redundant as having WHERE vs HAVING, i.e. they do the same things, but at different points in the execution plan. It feels weird to need two separate keywords for that.
SELECT * FROM (SELECT * FROM ... GROUP BY ...) t WHERE ...
SELECT * FROM ... GROUP BY ... HAVING ...
Another common case is projecting before the filter. E.g. you want to reuse a complicated expression in the SELECT and WHERE clauses. Standard SQL requires you to repeat it or use a subselect since the WHERE clause is evaluated first.
Personally I rarely use HAVING and instead use WHERE with subqueries for the following reasons:
1-I don't like repeating/duplicating a bunch of complex calcs, easier to just do WHERE in outer query on result
2-I typically have outer queries anyway for multiple reasons: break logic into reasonable chunks for humans, also for join+performance reasons (to give the optimizer a better chance at not getting confused)
Only if you aren't using a subquery otherwise you would use WHERE even in plain SQL. Since the pipe operator is effectively creating subqueries the syntax is perfectly consistent with SQL.
I will already use subqueries to avoid issues with HAVING.
We're moving from SQLAnywhere to MSSQL, and boy, we're adding 2-5 levels of subqueries to most non-trivial queries due to issues like that. Super annoying.
I had one which went from 2 levels deep to 9... not pleasant. CTEs had some issues so couldn't use those either.
One issue, that I mentioned in a different comment, is that we have a lot of queries which are used transparently as sub-queries at runtime to get count first, in order to limit rows fetched. The code doing the "transparent" wrapping doesn't have a full SQL parser, so can't hoist the CTEs out.
One performance issue I do recall was that a lateral join of a CTE was much, much slower than just doing 5-6 sub-queries of the same table, selecting different columns or aggregates for each. Think selecting sum packages, sum net weight, sum gross weight, sum value for all items on an invoice.
There were other issues using plain joins, but I can't recall them right now.
I like the idea of CTE's, but I typically use temp tables instead of CTE's to avoid optimizer issues.
You don't need a |> operator to make this possible. Your point is that there is a reason that SQL didn't just allow two WHERE clauses, one before and one after GROUP BY: to make it clearer syntactically.
Whereas the sort of proposal made by TFA is that if you think of the query as a sequence of steps to execute then you don't need the WHERE vs. HAVING clue because you can see whether a WHERE comes before or after GROUP BY in some query.
But the whole point of SQL is to _not have to_ think of how the query is to be implemented. Which I think brings us back to: it's better to have HAVING. But it's true also that it's better to allow arbitrary ordering of some clauses: there is no reason that FROM/JOIN, SELECT, ORDER BY / LIMIT have to be in the order that they are -- only WHERE vs. GROUP BY ordering matters, and _only_ if you insist on using WHERE for pre- and post-GROUP BY, but if you don't then all clauses can come in any order you like (though all table sources should come together, IMO).
So all in all I agree with you: keep HAVING.
I don't love the multiple WHEREs.
#!/bin/bash
function csv_to_parquet() {
file_path="$1"
duckdb -c "COPY (SELECT * FROM read_csv_auto('$file_path')) TO '${file_path%.*}.parquet' (FORMAT PARQUET);" }Could it be run on untrusted user input? Sure. Does it actually pose a threat? It's improbable.
So it would be reasonable to call it SQL, if it gets traction. You want to see some of the big dogs adopting it.
That should at least be possible since it looks like it could be added to an existing implementation without significant disruption/extra complexity.
The pipe operator is a semantic execution barrier:everything before the `|>` is assumed to have executed and returned a table before what follows begins:
From the paper:
> Each pipe operator is a unary relational operation that takes one table as input and produces one table as output.
Vanilla SQL is actually more complex in this respect because you have, for example, at least 3 different keywords for filtering (WHERE, HAVING, QUALIFY) and everyone who reads your query needs to understand what each keyword implies regarding execution scheduling. (WHERE is before grouping, HAVING is after aggregates, and QUALIFY is after analytic window functions.)
Other engines that implement it are direct competitors in that space: Snowflake, Databricks SQL, BigQuery, Clickhouse, and duckdb (only OSS implementation I now). Point is: if you want to compete with Teradata and be a possible migration target, you want to implement QUALIFY.
Anecdote: I went from a company that had Teradata to another where I had to implement all the data stack in GCP. I shed tears of joy when I knew BQ also had QUALIFY. And the intent was clear, as they also offered various Teradata migration services.
Isn't that FILTER (WHERE), as in SELECT avg(...) FILTER (WHERE ...) FROM ...?
If you're referring to this in the comment you're replying to:
> Can we call this SQL anymore after this? This re-ordering of things ...
Then they're clearly just saying that this is a reordering compared to SQL, which is undeniably true (and the while point).
I already think about SQL like this (as operation on lists/sets), however thinking of it like that, and having previous operations feed into the next, which is conceptually nice, seems to make it hard to do, and think about:
> *(the query engine is free to optimize the execution plan as long as the semantics are preserved)
since logically each part between the pipes doesn't know about the others, so global optimizations, such as use of indexes to restrict the result of a join based on the where clause can't be done/is more difficult.
But this thing resembles other FROM-clause-first variants of SQL, thus GP's point about this being just a reordering. GP is right: the FROM clause gets re-ordered to be first, so it's a reordering.
All these years I've been doing that reordering and didn't even realize!
Edit: nope, just that you don't need having to exist with the pipe syntax.
For clarity, they should have assigned #2 to a different variable letter.
query | operator
SELECT id,a,b FROM table WHERE id>1
|WHERE id < 10
PRQL gives me hope that we might finally get something nice some day
If the designers intended to create a query language that resembled an English sentence, it makes sense why they chose "SELECT FROM."
"Select the jar from the shelf" vs. "From the shelf, select the jar".
But I assume that that’s part of why they didn’t set it up that way — it’s just a little thing to make the query feel more declarative and less imperative
SELECT 1+2;
otoh if you selected something the from clause and potentially some joins could autocomplete
The changes to my SQL grammar to accomodate this proposal are minor. Move the 'from' rule to the front. Add a star '*' around a new filters rule (eg zero-or-more, in any order), removing the misc dialect specific alts, simplifying my grammar a bit.
Drop the pipes and this would be terrific.
Perhaps if they used a keyword PIPE and used a separate grammar definition for the statements that follow the pipe, such that it is almost what you’d expect but randomly missing things or changes up some keywords