You can check if what you need is available on a connection and either load it if needed or just abort:
sqlite> select * from pragma_function_list order by 1, 2; name builtin ------------------------- ---------- aavg 0 abs 1 acos 0 aggbitmask 0 aggmd2 0 aggmd4 0 aggmd5 0 aggsha1 0 aggsha256 0 aggsha2_256 0 aggsha2_384 0 aggsha2_512 0 aggsha384 0 aggsha3_224 0 aggsha3_256 0 aggsha3_384 0 aggsha3_512 0 aggsha512 0 ascw 0 asin 0 atan 0 atan2 0 avg 0 avg 1 avg_angle 0 avg_time 0 bitmask 0 bm25 0 ceil 0 changes 1 char 1 chgsign 0 chrw 0 ci 0 clrbits 0 coalesce 1 compress 0 computerfqdn 0 computername 0 copysign 0 cos 0 cosh 0 count 1 covar 0 cume_dist 1 current_date 0 current_date 1 current_time 0 current_time 1 current_timestamp 0 current_timestamp 1 date 0 date 1 datetime 0 datetime 1 datetimesec 0 degrees 0 delta_apply 0 delta_create 0 delta_output_size 0 dense_rank 1 doesfileexist 0 edit 0 editdist3 0 epsilon 0 eval 0 exp 0 exponent 0 fabs 0 feq 0 fge 0 fgt 0 first_value 1 firstnotnull 0 fle 0 flip 0 floor 0 flt 0 fmod 0 fne 0 fold 0 frac 0 fts3_tokenizer 0 fts5 0 fts5_decode 0 fts5_decode_none 0 fts5_expr 0 fts5_expr_tcl 0 fts5_fold 0 fts5_isalnum 0 fts5_rowid 0 fts5_source_id 0 gavg 0 geopoly_area 0 geopoly_bbox 0 geopoly_blob 0 geopoly_ccw 0 geopoly_contains_point 0 geopoly_debug 0 geopoly_group_bbox 0 geopoly_json 0 geopoly_overlap 0 geopoly_regular 0 geopoly_svg 0 geopoly_within 0 geopoly_xform 0 getfileattributes 0 glob 1 globu 0 group_concat 1 havg 0 havg_angle 0 hex 1 hexagesimal 0 hexw 0 highlight 0 hypot 0 ieee754 0 if 0 ifnull 1 instr 1 ipaddrblob 0 ipblobaddr 0 ipsubnetcontains 0 isclr 0 ismaskclr 0 ismaskset 0 isset 0 j0 0 j1 0 jn 0 json 0 json_array 0 json_array_length 0 json_extract 0 json_group_array 0 json_group_object 0 json_insert 0 json_object 0 json_patch 0 json_quote 0 json_remove 0 json_replace 0 json_set 0 json_type 0 json_valid 0 julianday 1 kurt 0 kurtp 0 lag 1 last_insert_rowid 1 last_value 1 lastnotnull 0 ldexp 0 lead 1 length 1 like 1 likelihood 1 likely 1 likeu 0 ln 0 load_extension 1 log 0 lookupname 0 lookupsid 0 lower 1 loweru 0 lsmode 0 ltrim 1 m_1_pi 0 m_2_pi 0 m_2_sqrtpi 0 m_deg2rad 0 m_e 0 m_ln10 0 m_ln2 0 m_log10e 0 m_log2e 0 m_pi 0 m_pi_2 0 m_pi_4 0 m_rad2deg 0 m_sqrt1_2 0 m_sqrt2 0 mantissa 0 match 0 matchinfo 0 max 1 md2 0 md2_query 0 md4 0 md4_query 0 md5 0 md5_query 0 median 0 min 1 mprint 0 mprint1 0 mprint2 0 mprint3 0 next_char 0 nth_value 1 ntile 1 nullif 1 offsets 0 olddatetime 0 olddatetimems 0 oldtime 0 oldunlocalize 0 oldunlocalizems 0 optimize 0 percent_rank 1 percentile 0 pow 0 prefix_length 0 printf 1 proper 0 quote 1 radians 0 random 1 randomblob 1 randomv 0 range 0 rank 1 ravg 0 readfile 0 regexp 0 replace 1 rms 0 rot13 0 round 1 roundhe 0 row_number 1 rtreecheck 0 rtreedepth 0 rtreenode 0 rtrim 1 sem 0 setbits 0 sha1 0 sha1_query 0 sha256 0 sha256_query 0 sha2_256 0 sha2_256_query 0 sha2_384 0 sha2_384_query 0 sha2_512 0 sha2_512_query 0 sha384 0 sha384_query 0 sha3_224 0 sha3_256 0 sha3_384 0 sha3_512 0 sha3_query 0 sha512 0 sha512_query 0 shell_add_schema 0 shell_escape_crnl 0 shell_int32 0 shell_module_schema 0 shell_putsnl 0 sign 0 sin 0 sinh 0 skew 0 skewp 0 snippet 0 soundex 1 spellfix1_editdist 0 spellfix1_phonehash 0 spellfix1_scriptcode 0 spellfix1_translit 0 sqlar_compress 0 sqlar_uncompress 0 sqlite_compileoption_get 1 sqlite_compileoption_used 1 sqlite_log 1 sqlite_record 1 sqlite_source_id 1 sqlite_version 1 sqrt 0 stdev 0 stdevp 0 strdup 0 strfilter 0 strftime 1 strpos 0 strtaboo 0 substr 1 sum 1 tan 0 tanh 0 time 0 time 1 timebeginperiod 0 timeendperiod 0 title 0 tointeger 0 tokenhasname 0 tokenhassid 0 toreal 0 total 1 total_changes 1 trim 1 trunc 0 typeof 1 typos 0 ulp 0 ulps 0 unaccent 0 uncompress 0 unicode 1 unifuzz 0 unixinstant 0 unixtime 0 unlikely 1 unlocaldate 0 unlocalize 0 unzorder 0 upper 1 upperu 0 username 0 usersid 0 uuidcreatev1 0 uuidcreatev4 0 uuidfromstring 0 uuidstringcreatev1 0 uuidstringcreatev4 0 uuidtostring 0 var 0 varp 0 writefile 0 y0 0 y1 0 yn 0 zeroblob 1 zipfile 0 zipfile_cds 0 zorder 0 sqlite> select * from pragma_collation_list order by 1, 2; seq name ------------------------- ---------- 0 ROT13 1 NUMERICS 2 UNACCENTED 3 NAMES 4 NOCASEU 5 IPADDRESS 6 RTRIM 7 NOCASE 8 BINARY sqlite> select * from pragma_module_list order by 1; name ------------------------- approximate_match carray completion csv dbstat delta_parse fsdir fts3 fts3tokenize fts4 fts4aux fts5 fts5vocab fuzzer generate_series geopoly interpolate json_each json_tree pragma_collation_list pragma_function_list pragma_module_list prefixes rtree rtree_i32 spellfix1 sqlite_btreeinfo sqlite_dbdata sqlite_dbpage sqlite_dbptr sqlite_memstat sqlite_stmt swarmvtab transitive_closure unionvtab wholenumber zipfile sqlite> select * from pragma_compile_options; compile_options ALLOW_COVERING_INDEX_SCAN ALLOW_URI_AUTHORITY COMPILER=gcc-8.1.0 DATETIME_NEW DEFAULT_CACHE_SIZE=262144 DEFAULT_FOREIGN_KEYS DEFAULT_MMAP_SIZE=0 DEFAULT_PAGE_SIZE=4096 DEFAULT_PROXYDIR_PERMISSIONS=0755 DEFAULT_RECURSIVE_TRIGGERS DEFAULT_WAL_AUTOCHECKPOINT=256 DEFAULT_WAL_SYNCHRONOUS=1 DEFAULT_WORKER_THREADS=8 ENABLE_8_3_NAMES=1 ENABLE_API_ARMOR ENABLE_COLUMN_METADATA ENABLE_COLUMN_USED_MASK ENABLE_COSTMULT ENABLE_CURSOR_HINTS ENABLE_DBSTAT_VTAB ENABLE_FTS3 ENABLE_FTS3_PARENTHESIS ENABLE_FTS4 ENABLE_FTS5 ENABLE_GEOPOLY ENABLE_JSON1 ENABLE_LOAD_EXTENSION ENABLE_LOCKING_STYLE=1 ENABLE_MEMORY_MANAGEMENT ENABLE_NORMALIZE ENABLE_PREUPDATE_HOOK ENABLE_RBU ENABLE_RTREE ENABLE_STAT4 ENABLE_STMTVTAB ENABLE_STMT_SCANSTATUS EXPLAIN_ESTIMATED_ROWS EXTRA_INIT=core_init HAVE_ISNAN LIKE_DOESNT_MATCH_BLOBS MAX_ATTACHED=15 MAX_WORKER_THREADS=8 PRECISE_TIME SOUNDEX TEMP_STORE=1 THREADSAFE=1 USE_URI --- The fact that there's a Highway to Hell but only a Stairway to Heaven says a lot about anticipated traffic volume. >-----Original Message----- >From: sqlite-users [mailto:sqlite-users- >boun...@mailinglists.sqlite.org] On Behalf Of Thomas Kurz >Sent: Wednesday, 22 May, 2019 22:19 >To: SQLite mailing list >Subject: Re: [sqlite] SQL Features That SQLite Does Not Implement > >I agree in that not every math function can be included by default. >My problem, however, is that I cannot know whether a user uses my >self-compiled version with built-in extension-functions.c, or a >downloaded version from sqlite.org. > >It would be very, very helpful (especially regarding views!) to have >some kind of a "check function" so that one could write > >SELECT CASE WHEN defined('stddev') THEN stddev(foo) ELSE NULL END >FROM bar > > >----- Original Message ----- >From: Keith Medcalf <kmedc...@dessus.com> >To: SQLite mailing list <sqlite-users@mailinglists.sqlite.org> >Sent: Wednesday, May 22, 2019, 22:20:11 >Subject: [sqlite] SQL Features That SQLite Does Not Implement > > >On Wednesday, 22 May, 2019 11:51, sky5w...@gmail.com wrote: > >>Please add a note to the omitted page that many basic math functions >>are NOT supported. (sqrt,mod,power,stdev,etc.) > >Traditionally "math library" functions provided by the various >language runtimes were not included becase this would introduce >dependancies on a "math library". While this is available on *most* >platforms, it is not available on *all* platforms which SQLite3 can >be compiled for out of the box. Furthermore the implementation of >some transcendentals may be intrinsic on some CPU's and require huge >amounts of library code on others. Statistical functions are not >included because, well, they require complex implementations to get >right. > >Moreover, even the builtin functions are "lite" (the round function >does not round properly for instance (it does grade-school 4/5 >rounding rather than half-even rounding), the average function is >rather simple in implementation and suffers from trivally triggered >sources of computational error (it uses sum/count rather than >successive approximation to the mean), and many other limitations >exist in the builtin implementations of many functions). > >All of these issues can be "fixed" however, all you need to do is add >the necessary code via the extension mechanism to add whatever >functionality you require using whatever numerical methods you >determine are suitable for your needs. For example, I have added >default support via the extension mechanism (and the EXTRA_INIT hook) >to make all the distributed extensions available on every connection, >to add all the standard platform math functions, to add a bunch of >statistical functions, several platform APIs (Windows in this case), >and to "fix" the builtin round, datetime (to include proper support >for instant times and timezone manipulation using the standard IANA >timezone database), and added support for basic Unicode nocase and >noaccent collations without using the whole ICU library. > >The downside of this is that the implementation of all these >"goodies" quadruples the size of the base engine code (sqlite3.obj) >and it is no longer "Lite". There are other drawbacks as well. For >example, it is difficult to make many advanced numerical calculation >methods (aggregates) compatible with window functions as currently >implemented. > >About the only thing that is missing from SQLite3 is the ability to >declare and implement "user defined types" in a fully integrated way >(such as was added to DB2 back in the late 80's early 90's, and which >I do not think anyone else has implemented as nicely anywhere else). > >Really, the issue is that SQLite3 is an SQL based relational storage >manager, and it implements this function very well. It does not >provide a huge array of accoutrements that you may see with other >more ex$pen$ive RDMS systems, but does provide the ability to add >(most of) those accoutrements if you wish. > >--- >The fact that there's a Highway to Hell but only a Stairway to Heaven >says a lot about anticipated traffic volume. > > > > > >_______________________________________________ >sqlite-users mailing list >sqlite-users@mailinglists.sqlite.org >http://mailinglists.sqlite.org/cgi-bin/mailman/listinfo/sqlite-users > >_______________________________________________ >sqlite-users mailing list >sqlite-users@mailinglists.sqlite.org >http://mailinglists.sqlite.org/cgi-bin/mailman/listinfo/sqlite-users _______________________________________________ sqlite-users mailing list sqlite-users@mailinglists.sqlite.org http://mailinglists.sqlite.org/cgi-bin/mailman/listinfo/sqlite-users
