Re: Tackling JsonPath support

<div dir="ltr"><div class="gmail_extra"><div class="gmail_quote">On Mon, Nov 28, 2016 at 9:40 AM, Pavel Stehule <span
dir="ltr"><<ahref="mailto:pavel.stehule@gmail.com" target="_blank">pavel.stehule@gmail.com</a>></span>
wrote:</div><divclass="gmail_quote"><div class="gmail_default"
style="font-family:arial,helvetica,sans-serif">​...​</div><blockquoteclass="gmail_quote" style="margin:0 0 0
.8ex;border-left:1px#ccc solid;padding-left:1ex"><p dir="ltr"><span class="">> ​Hi Pavel,<br /> ><br /> > Can
youclarify what you meant?  I *think* you're saying:<br /> ><br /> > * It's not important for me to match the
syntax/semanticsof the json-path implementations found in MySQL / Oracle / DB2 / ​MS SQL Server, and<br />
></span><pdir="ltr">oh no. the syntax is important. But for start we can have a subset. For json table function ..
jsonto relation mapping is important path expression. some other features like predicates<br /> are nice, but can be
implementedlater.<p dir="ltr">Im sorry. My English is bad.</blockquote><div class="gmail_default"
style="font-family:arial,helvetica,sans-serif">​HiPavel,</div><div class="gmail_default"
style="font-family:arial,helvetica,sans-serif"><br/></div><div class="gmail_default"
style="font-family:arial,helvetica,sans-serif">You'reEnglish is very good, actually.  I think the confusion arises from
mespeaking in vague terms.  I apologize for that.  Allow me to be more specific about what I'm proposing to
do.</div><divclass="gmail_default" style="font-family:arial,helvetica,sans-serif"><br /></div><div
class="gmail_default"style="font-family:arial,helvetica,sans-serif">I propose adding to "contrib" a function with the
followingcharacteristics:</div><div class="gmail_default" style="font-family:arial,helvetica,sans-serif"><br
/></div><divclass="gmail_default" style="font-family:arial,helvetica,sans-serif">* Its signature is "json_path( jsonb
from_json,string json_path_expression) --> jsonb".</div><div class="gmail_default"
style="font-family:arial,helvetica,sans-serif"><br/></div><div class="gmail_default"
style="font-family:arial,helvetica,sans-serif">*The function will hopefully be a useful building block for PG's
implementationof "official" JSON operators such as "JSON_TABLE".  Once the PG community agrees on what those operators'
syntax/semanticsshould be.</div><div class="gmail_default" style="font-family:arial,helvetica,sans-serif">​</div><div
class="gmail_default"style="font-family:arial,helvetica,sans-serif">* The function will hopefully be immediately useful
toPG users who want JSONPath -like operations on their "jsonb" objects.</div><div class="gmail_default"
style="font-family:arial,helvetica,sans-serif"><br/></div><div class="gmail_default"
style="font-family:arial,helvetica,sans-serif">-C</div></div></div></div>