Обсуждение: remove bits* types
(new thread) On Wed, Mar 18, 2026 at 04:17:40PM -0500, Nathan Bossart wrote: > On Tue, Mar 17, 2026 at 05:09:49PM -0400, Andres Freund wrote: >> Personally I object to the existence of the bits* types, to me they're just >> noise over using the corresponding unsigned integer types. One more thing that >> one has to just know what it means without there being any actual improved >> type checking or such. It's not like using bits* would make it any easier to >> make the underlying type a struct or such (which is different to >> e.g. TransactionId, we could probably replace that with a struct without crazy >> amounts of trouble). > > Yeah, I don't see why you'd prefer bits32 over uint32. If anything, uint32 > is probably less confusing because most hackers will have used it before. > AFAICT the bits* types are a relic of the 80s, and there used to be other > types like bool8 and word32, all of which were just uint* behind the > scenes. Those were removed in 2004 by commit ca7a1f0c86. I assume bits* > was left behind because it was still in use. > >> I think we should just rip the bits* types out and replace them with the >> underlying types. > > +1. If there seems to be consensus, I'm happy to write the patch. Well, in the process of seeing how bad the patch would look, I ended up writing it. I used sed for most of this, and I tried to make all necessary manual adjustments, but I may have missed a couple. -- nathan
Вложения
On 2026-Mar-18, Nathan Bossart wrote: > Well, in the process of seeing how bad the patch would look, I ended up > writing it. I used sed for most of this, and I tried to make all necessary > manual adjustments, but I may have missed a couple. Shrug. As I said in the other thread, it seems mildly useful to distinguish the cases where stuff is there solely to be treated as a mask of independent bits instead of something you do arithmetic with. But if nobody else likes this, I won't stand in your way. -- Álvaro Herrera Breisgau, Deutschland — https://www.EnterpriseDB.com/ "No tengo por qué estar de acuerdo con lo que pienso" (Carlos Caszeli)
=?utf-8?Q?=C3=81lvaro?= Herrera <alvherre@kurilemu.de> writes:
> Shrug. As I said in the other thread, it seems mildly useful to
> distinguish the cases where stuff is there solely to be treated as a
> mask of independent bits instead of something you do arithmetic with.
I could get behind that if we were declaring bitmask variables using
bitsNN more or less consistently, but if we do that at all it's a
minority usage. I didn't even realize there was any such convention.
A lot of the places Nathan is changing don't look like they are
following such a convention anyway.
In short: maybe we don't want to go in the direction Nathan suggests,
but if we keep these types we should make an effort to use them
more consistently, so there's work to be done in that direction too.
regards, tom lane
On Wed, Mar 18, 2026 at 6:41 PM Tom Lane <tgl@sss.pgh.pa.us> wrote: > In short: maybe we don't want to go in the direction Nathan suggests, > but if we keep these types we should make an effort to use them > more consistently, so there's work to be done in that direction too. I'm definitely -1 on trying to use them more consistently. This is a 261 line patch. The reverse patch to use these types everywhere that we use integers as a collection of bits is probably 100 times that size. If you took that idea to its logical conclusion, every flags variable in the backend would end up getting converted. I'm not entirely sure that this is worth standardizing at all; if someone thinks that using bits8 or whatever makes the code more rather than less clear in a certain context, who am I to argue? If someone else prefers uint8 in another context, also fine. But if we are going to standardize, I think the only sensible choice is what Nathan's done here. The reverse would be an insane amount of code churn. -- Robert Haas EDB: http://www.enterprisedb.com
On 2026-Mar-18, Robert Haas wrote: > I'm not entirely sure that this is worth standardizing at all; if > someone thinks that using bits8 or whatever makes the code more rather > than less clear in a certain context, who am I to argue? If someone > else prefers uint8 in another context, also fine. I don't think we _have_ to force our hand one way or the other. -- Álvaro Herrera 48°01'N 7°57'E — https://www.EnterpriseDB.com/ "It takes less than 2 seconds to get to 78% complete; that's a good sign. A few seconds later it's at 90%, but it seems to have stuck there. Did somebody make percentages logarithmic while I wasn't looking?" http://smylers.hates-software.com/2005/09/08/1995c749.html
On Wed, Mar 18, 2026 at 07:15:29PM -0400, Robert Haas wrote:
> I'm definitely -1 on trying to use them more consistently. This is a
> 261 line patch. The reverse patch to use these types everywhere that
> we use integers as a collection of bits is probably 100 times that
> size. If you took that idea to its logical conclusion, every flags
> variable in the backend would end up getting converted.
This is definitely not accurate, but I counted around 400 such cases for
the reverse patch:
$ grep -E "int[0-9]* (flags|options)" src/* -rI | wc -l
409
> I'm not entirely sure that this is worth standardizing at all; if
> someone thinks that using bits8 or whatever makes the code more rather
> than less clear in a certain context, who am I to argue? If someone
> else prefers uint8 in another context, also fine.
>
> But if we are going to standardize, I think the only sensible choice
> is what Nathan's done here. The reverse would be an insane amount of
> code churn.
While nobody seems totally opposed to the idea, it does seem to be
generating some discussion. I'd rather not distract more important work
for v19, so I'm happy to put it on the shelf for now.
--
nathan
=?utf-8?Q?=C3=81lvaro?= Herrera <alvherre@kurilemu.de> writes:
> On 2026-Mar-18, Robert Haas wrote:
>> I'm not entirely sure that this is worth standardizing at all; if
>> someone thinks that using bits8 or whatever makes the code more rather
>> than less clear in a certain context, who am I to argue? If someone
>> else prefers uint8 in another context, also fine.
> I don't think we _have_ to force our hand one way or the other.
I'm content with the status quo personally, but perhaps it'd be
worth adding some info to the comment for the bitsNN typedefs
to make it clearer what they are intended for. I'm imagining
something along the lines of
/*
* bitsN
* Unit of bitwise operation, AT LEAST N BITS IN SIZE.
+ *
+ * Use these type names for values that are intended to be manipulated
+ * as sets of bits, for example bitmasks of flags, null bitmaps, etc.
+ * If it'd be sensible to do arithmetic on it, it's not a set of bits.
*/
typedef uint8 bits8; /* >= 8 bits */
typedef uint16 bits16; /* >= 16 bits */
typedef uint32 bits32; /* >= 32 bits */
regards, tom lane
On Thu, Mar 19, 2026 at 12:22:10PM -0400, Tom Lane wrote: > I'm content with the status quo personally, but perhaps it'd be > worth adding some info to the comment for the bitsNN typedefs > to make it clearer what they are intended for. I'm imagining > something along the lines of Not sure why we absolutely need to be aggressive with a removal here, so I'm +/-0 on that. And there is always the argument of breaking the compilation of out-of-core code. That would be easily fixable, still always slightly annoying. -- Michael