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mdbx-doc: add the output of limits to the mdbx_example.

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Change-Id: I1bbe194e80f888c37a6a082927444b6897babcc4
This commit is contained in:
Leonid Yuriev 2021-03-17 01:25:28 +03:00
parent 6c9e8817b7
commit 2149d893bc
1 changed files with 49 additions and 0 deletions
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49
example/example-mdbx.c
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@ -19,6 +19,8 @@
*/ */
#include "mdbx.h" #include "mdbx.h"
#include <limits.h>
#include <stdint.h>
#include <stdio.h> #include <stdio.h>
#include <stdlib.h> #include <stdlib.h>
@ -34,6 +36,53 @@ int main(int argc, char *argv[]) {
MDBX_cursor *cursor = NULL; MDBX_cursor *cursor = NULL;
char sval[32]; char sval[32];
printf("MDBX limits:\n");
#if UINTPTR_MAX > 0xffffFFFFul || ULONG_MAX > 0xffffFFFFul
const double scale_factor = 1099511627776.0;
const char *const scale_unit = "TiB";
#else
const double scale_factor = 1073741824.0;
const char *const scale_unit = "GiB";
#endif
const size_t pagesize_min = mdbx_limits_pgsize_min();
const size_t pagesize_max = mdbx_limits_pgsize_max();
const size_t pagesize_default = mdbx_default_pagesize();
printf("\tPage size: a power of 2, minimum %zu, maximum %zu bytes,"
" default %zu bytes.\n",
pagesize_min, pagesize_max, pagesize_default);
printf("\tKey size: minimum %zu, maximum ≈¼ pagesize (%zu bytes for default"
" %zuK pagesize, %zu bytes for %zuK pagesize).\n",
(size_t)0, mdbx_limits_keysize_max(-1, MDBX_DB_DEFAULTS),
pagesize_default / 1024,
mdbx_limits_keysize_max(pagesize_max, MDBX_DB_DEFAULTS),
pagesize_max / 1024);
printf("\tValue size: minimum %zu, maximum %zu (0x%08zX) bytes for maps,"
" ≈¼ pagesize for multimaps (%zu bytes for default %zuK pagesize,"
" %zu bytes for %zuK pagesize).\n",
(size_t)0, mdbx_limits_valsize_max(pagesize_min, MDBX_DB_DEFAULTS),
mdbx_limits_valsize_max(pagesize_min, MDBX_DB_DEFAULTS),
mdbx_limits_valsize_max(-1, MDBX_DUPSORT), pagesize_default / 1024,
mdbx_limits_valsize_max(pagesize_max, MDBX_DUPSORT),
pagesize_max / 1024);
printf("\tWrite transaction size: up to %zu (0x%zX) pages (%f %s for default "
"%zuK pagesize, %f %s for %zuK pagesize).\n",
mdbx_limits_txnsize_max(pagesize_min) / pagesize_min,
mdbx_limits_txnsize_max(pagesize_min) / pagesize_min,
mdbx_limits_txnsize_max(-1) / scale_factor, scale_unit,
pagesize_default / 1024,
mdbx_limits_txnsize_max(pagesize_max) / scale_factor, scale_unit,
pagesize_max / 1024);
printf("\tDatabase size: up to %zu pages (%f %s for default %zuK "
"pagesize, %f %s for %zuK pagesize).\n",
mdbx_limits_dbsize_max(pagesize_min) / pagesize_min,
mdbx_limits_dbsize_max(-1) / scale_factor, scale_unit,
pagesize_default / 1024,
mdbx_limits_dbsize_max(pagesize_max) / scale_factor, scale_unit,
pagesize_max / 1024);
printf("\tMaximum sub-databases: %u.\n", MDBX_MAX_DBI);
printf("-----\n");
rc = mdbx_env_create(&env); rc = mdbx_env_create(&env);
if (rc != MDBX_SUCCESS) { if (rc != MDBX_SUCCESS) {
fprintf(stderr, "mdbx_env_create: (%d) %s\n", rc, mdbx_strerror(rc)); fprintf(stderr, "mdbx_env_create: (%d) %s\n", rc, mdbx_strerror(rc));